[karp] draft-lebovitz-kmart-roadmap-03.txt attached
"Gregory M. Lebovitz" <gregory.ietf@gmail.com> Wed, 04 November 2009 20:19 UTC
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To: karp@ietf.org, Ross Callon <rcallon@juniper.net>, "Joel M. Halpern" <jmh@joelhalpern.com>, Brian Weis <bew@cisco.com>, tim Polk <tim.polk@nist.gov>
From: "Gregory M. Lebovitz" <gregory.ietf@gmail.com>
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Subject: [karp] draft-lebovitz-kmart-roadmap-03.txt attached
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Hey all,
I just finished an update to the document. It is attached, and pasted below.
The Chairs will put the link to the email archive page of this
message in the BoF page, and BoF Agenda page too, so that people can
find the document easily. We'll get it posted to I-D repository as
soon as the window opens on Monday.
Editor's Note on "KMART" vs "KARP": The first few versions of this
document were called "draft-lebovitz-kmart-roadmap-xx". Upon the
creation of the BoF for IETF76, the IESG requested the name of the
effort change so as to avoid any potential trademark issues. The new
name of the effort is KARP. Version -03 will go out titled with the
old KMART "draft-lebovitz-kmart-roadmap-03", so as to avoid
confusion, but within the document text you'll find
s/kmart/karp/. As soon as the I-D editor queue opens again (Monday,
09 Nov) the document will be submitted with s/kmart/karp/ in the title too.
Also, we are well aware that the current draft is very much a
catch-all. That was by design. We will be breaking up this document
into a few smaller docs, post Hiroshima, something like:
- Guidance to Routing Protocol Authentication Design Teams
- Threats
- Requirements (maybe combined with threats?)
- Framework
So please be thinking as you review it if you would like to co-author
any of those documents. I'll probably keep lead editor role on the
Framework document, and maybe one other, but invite co-editors even on those.
See you soon,
Gregory.
= = = = BEGIN PASTE OF DOCUMENT = = = =
KARP G. Lebovitz
Internet-Draft Juniper
Intended status: Informational November 05, 2009
Expires: May 9, 2010
Roadmap for Cryptographic Authentication of Routing Protocol Packets on
the Wire
draft-lebovitz-kmart-roadmap-03
Abstract
In the March of 2006 the IAB held a workshop on the topic of
"Unwanted Internet Traffic". The report from that workshop is
documented in RFC 4948 [RFC4948]. Section 8.2 of RFC 4948 calls for
"[t]ightening the security of the core routing infrastructure." Four
main steps were identified for improving the security of the routing
infrastructure. One of those steps was "securing the routing
protocols' packets on the wire." One mechanism for securing routing
protocol packets on the wire is the use of per-packet cryptographic
message authentication, providing both peer authentication and
message integrity. Many different routing protocols exist and they
employ a range of different transport subsystems. Therefore there
must necessarily be various methods defined for applying
cryptographic authentication to these varying protocols. Many
routing protocols already have some method for accomplishing
cryptographic message authentication. However, in many cases the
existing methods are dated, vulnerable to attack, and/or employ
cryptographic algorithms that have been deprecated. This document
creates a roadmap of protocol specification work for the use of
modern cryptogrpahic mechanisms and algorithms for message
authentication in routing protocols. It also defines the framework
for a key management protocol that may be used to create and manage
session keys for message authentication and integrity. This roadmap
reflects the input of both the security area and routing area in
order to form a jointly agreed upon and prioritized work list for the
effort.
Status of this Memo
This Internet-Draft is submitted to IETF in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that
other groups may also distribute working documents as Internet-
Drafts.
Lebovitz & Expires May 9, 2010 [Page 1]
Internet-Draft KARP Roadmap November 2009
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt.
The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html.
This Internet-Draft will expire on May 9, 2010.
Copyright Notice
Copyright (c) 2009 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the BSD License.
Lebovitz & Expires May 9, 2010 [Page 2]
Internet-Draft KARP Roadmap November 2009
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 5
1.2. Requirements Language . . . . . . . . . . . . . . . . . . 6
1.3. Scope . . . . . . . . . . . . . . . . . . . . . . . . . . 6
1.4. Goals . . . . . . . . . . . . . . . . . . . . . . . . . . 8
1.5. Non-Goals . . . . . . . . . . . . . . . . . . . . . . . . 11
1.6. Audience . . . . . . . . . . . . . . . . . . . . . . . . . 12
2. Threats . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
2.1. Threats In Scope . . . . . . . . . . . . . . . . . . . . . 13
2.2. Threats Out of Scope . . . . . . . . . . . . . . . . . . . 15
3. Categorizing Routing Protocols . . . . . . . . . . . . . . . . 16
3.1. Category: Messaging Transaction Type . . . . . . . . . . . 16
3.2. Category: Peer vs. Group Keying . . . . . . . . . . . . . 17
3.3. Category: Update vs. Discovery Protocol . . . . . . . . . 18
3.4. Security Characterization Vectors . . . . . . . . . . . . 18
3.4.1. Internal vs. External Operation . . . . . . . . . . . 18
3.4.2. Unique versus Shared Keys . . . . . . . . . . . . . . 19
3.4.3. Out-of-Band vs. In-line Key Management . . . . . . . . 20
4. The Roadmap . . . . . . . . . . . . . . . . . . . . . . . . . 22
4.1. Work Phases on any Particular Protocol . . . . . . . . . . 22
4.2. Requirements for Phase 1 Routing Protocols' Security
Update . . . . . . . . . . . . . . . . . . . . . . . . . . 24
4.3. Common Framework . . . . . . . . . . . . . . . . . . . . . 25
4.4. Work Items Per Routing Protocol . . . . . . . . . . . . . 31
4.5. Protocols in Categories . . . . . . . . . . . . . . . . . 33
4.6. Priorites . . . . . . . . . . . . . . . . . . . . . . . . 35
5. Security Considerations . . . . . . . . . . . . . . . . . . . 35
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 37
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 37
8. Change History (RFC Editor: Delete Before Publishing) . . . . 37
9. Needs Work in Next Draft (RFC Editor: Delete Before
Publishing) . . . . . . . . . . . . . . . . . . . . . . . . . 40
10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 41
10.1. Normative References . . . . . . . . . . . . . . . . . . . 41
10.2. Informative References . . . . . . . . . . . . . . . . . . 41
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 42
Lebovitz & Expires May 9, 2010 [Page 3]
Internet-Draft KARP Roadmap November 2009
1. Introduction
In March 2006 the Internet Architecture Board (IAB) held a workshop
on the topic of "Unwanted Internet Traffic". The report from that
workshop is documented in RFC 4948 [RFC4948]. Section 8.1 of that
document states that "A simple risk analysis would suggest that an
ideal attack target of minimal cost but maximal disruption is the
core routing infrastructure." Section 8.2 calls for "[t]ightening
the security of the core routing infrastructure." Four main steps
were identified for that tightening:
o More secure mechanisms and practices for operating routers. This
work is being addressed in the OPSEC Working Group.
o Cleaning up the Internet Routing Registry repository [IRR], and
securing both the database and the access, so that it can be used
for routing verifications. This work should be addressed through
liaisons with those running the IRR's globally.
o Specifications for cryptographic validation of routing message
content. This work will likely be addressed in the SIDR Working
Group.
o Securing the routing protocols' packets on the wire
This document addresses the last bullet, securing the packets on the
wire of the routing protocol exchanges. The document addresses
Keying and Authentication for Routing Protocols, aka "KARP".
It is unlikely that this document, in its current form, will become
an RFC. More likely is that this document will be split up into
several smaller documents which may look something like:
o Scope & Goals sections will likely become part of the KARP WG
charter
o Threat document
o Requirements document (may be combined with Threat document)
o Framework document
o RoutingProtocol Design Team Work Plan document. This would
include sections like Work Phases, Priorities, Security
Considerations, etc.
For now, the document serves as the catch all for the set of thoughts
around the KARP effort. As a working group is formed, decisions will
be made about the creation of specific documents.
Editor's Note on "KMART" vs "KARP": The first few versions of this
document were called "draft-lebovitz-kmart-roadmap-xx". Upon the
creation of the BoF for IETF76, the IESG requested the name of the
effort change so as to avoid any potential trademark issues. The new
name of the effort is KARP. Version -03 will go out titled
"draft-lebovitz-kmart-roadmap-03", so as to avoid confusion. As soon
Lebovitz & Expires May 9, 2010 [Page 4]
Internet-Draft KARP Roadmap November 2009
as the I-D editor queue opens again (Monday, 09 Nov) the document
will be submitted with s/kmart/karp/ in the title.
1.1. Terminology
Within the scope of this document, the following words, when
beginning with a capital letter, or spelled in all capitals, hold the
meanings described to the right of each term. If the same word is
used uncapitalized, then it is intended to have its common english
definition.
PSK Pre-Shared Key. A key used by both peers in a secure
configuration. Usually exchanged out-of-band prior to
a first connection.
Routing Protocol When used with capital "R" and "P" in this document
the term refers the Routing Protocol for which work is
being done to provide or enhance its peer
authentication mechanisms.
PRF Pseudorandom number function, or sometimes called
pseudorandom number generator (PRNG). An algorithm
for generating a sequence of numbers that approximates
the properties of random numbers. The sequence is not
truly random, in that it is completely determined by a
relatively small set of initial values that are passed
into the function. An exmaple is SHA-256.
KDF Key derivation function. A particular specified use
of a PRF that takes a PSK, combines it with other
inputs to the PRF, and produces a result that is
suitable for use as a Traffic Key.
Identifier The type and value used by one peer of an
authenticated message exchange to signify to the other
peer who they are. The Identifier is used by the
receiver as a lookup index into a table containing
further information about the peer that is required to
continue processing the message, for example a
Security Association (SA) or keys.
Identity Proof A cryptographic proof for an asserted identity, that
the peer really is who they assert themselves to be.
Proof of identity can be arranged between the peers in
a few ways, for example PSK, raw assymetric keys, or a
more user-friendly representation of assymetric keys,
like a certificate.
Lebovitz & Expires May 9, 2010 [Page 5]
Internet-Draft KARP Roadmap November 2009
Security Association or SA The parameters and keys that together
form the required information for processing secure
sessions between peers. Examples of items that may
exist in an SA include: Identifier, PSK, Traffic Key,
cryptographic algorithms, key lifetimes.
KMP Key Management Protocol. A protocol used between
peers to exchange SA parameters and Traffic Keys.
Examples of KMPs include IKE, TLS, and SSH.
KMP Function Any actual KMP used in the general KARP solution
framework
Peer Key Keys that are used between peers as the identity
proof. These keys may or may not be connection
specific, depending on who they were established, and
what form of identity and identity proof is being used
in the system.
Traffic Key The actual key used on each packet of a message.
Definitions of items specific to the general KARP framework are
described in more detail in the Framework section Section 4.3.
1.2. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC2119 [RFC2119].
When used in lower case, these words convey their typical use in
common language, and are not to be interpreted as described in
RFC2119 [RFC2119].
1.3. Scope
Four basic tactics may be employed in order to secure any piece of
data as it is transmitted over the wire: privacy (or encryption),
authentication, message integrity, and non-repudiation. The focus
for this effort, and the scope for this roadmap document, will be
message authentication and packet integrity only. This work
explicitly excludes, at this point in time, the other two tactics:
privacy and non-repudiation. Since the objective of most routing
protocols is to broadly advertise the routing topology, routing
messages are commonly sent in the clear; confidentiality is not
normally required for routing protocols. However, ensuring that
routing peers truly are the trusted peers expected, and that no roque
Lebovitz & Expires May 9, 2010 [Page 6]
Internet-Draft KARP Roadmap November 2009
peers or messages can compromise the stability of the routing
environment is critical, and thus our focus. The other two
explicitly excluded tactics, privacy and non-repudiation, may be
addressed in future work.
It is possible for routing protocol packets to be transmitted
employing all four security tactics mentioned above using existing
standards. For example, one could run unicast, layer 3 or above
routing protocol packets through IPsec ESP [RFC4303]. This would
provide the added benefit of privacy, and non-repudiation. However,
router platforms and systems have been fine tuned over the years for
the specific processing necessary for routing protocols' non-
encapsulated formats. Operators are, therefore, quite reluctant to
explore new packet encapsulations for these tried and true protocols.
In addition, at least in the case of BGP and LDP, these protocols
already have existing mechanisms for cryptographically authenticating
and integrity checking the packets on the wire. Products with these
mechanisms have already been produced, code has already been written
and both have been optimized for the existing mechanisms. Rather
than turn away from these mechanisms, we want to enhance them,
updating them to modern and secure levels.
There are two main work phases for this roadmap, and for any Routing
Protocol work undertaken as part of this roadmap (discussed further
in the Work Phases (Section 4.1) section). The first is to enhance
the Routing Protocol's current authentication mechanism, ensuring it
employs modern cryptographic algorithms and methods for its basic
operational model, fulfilling the requirements defined in the
Requirements (Section 4.2) section, and protecting against as many of
the threats as possible as defined in the Threats (Section 2.1)
section. Many of the Routing Protocols' current mechanisms use
manual keys, so the first phase updates will focus on shoring up the
manual key mechanisms that exist.
The second work phase is to define the use of a key management
protocol (KMP) for creating and managing session keys used in the
Routing Protocols' message authentication and data integrity
functions. It is intended that a general KMP framework -- or a small
number of frameworks -- can be defined and leveraged for many Routing
Protocols.
Therefore, the scope of this roadmap of work includes:
Lebovitz & Expires May 9, 2010 [Page 7]
Internet-Draft KARP Roadmap November 2009
o Making use of existing routing protocol security protocols, where
they exist, and enhancing or updating them as necessary for modern
cryptographic best practices,
o Developing a framework for using automatic key management in order
to ease deployment, lower cost of operation, and allow for rapid
responses to security breaches, and
o Specifying the automated key management protocol that may be
combined with the bits-on-the-wire mechanisms.
The work also serves as an agreement between the Routing Area and the
Security Area about the priorities and work plan for incrementally
delivering the above work. This point is important. There will be
times when the best-security-possible will give way to vastly-
improved-over-current-security-but-admittedly-not-yet-best-security-
possible, in order that incremental progress toward a more secure
Internet may be achieved. As such, this document will call out
places where agreement has been reached on such trade offs.
This document does not contain protocol specifications. Instead, it
defines the areas where protocol specification work is needed and
sets a direction, a set of requirements, and a relative priority for
addressing that specification work.
There are a set of threats to routing protocols that are considered
in-scope for this document/roadmap, and a set considered out-of-
scope. These are described in detail in the Threats (Section 2)
section below.
1.4. Goals
The goals and general guidance for this work roadmap follow:
1. Provide authentication and integrity protection for packets on the
wire of existing routing protocols
2. Deliver a path to incrementally improve security of the routing
infrastructure. The principle of crawl, walk, run will be in
place. Routing protocol authentication mechanisms may not go
immediately from their current state to a state containing the
best possible, most modern security practices. Incremental steps
will need to be taken for a few very practical reasons. First,
there are a considerable number of deployed routing devices in
operating networks that will not be able to run the most modern
cryptographic mechanisms without significant and unacceptable
performance penalties. The roadmap for any one routing protocol
MUST allow for incremental improvements on existing operational
Lebovitz & Expires May 9, 2010 [Page 8]
Internet-Draft KARP Roadmap November 2009
devices. Second, current routing protocol performance on deployed
devices has been achieved over the last 20 years through extensive
tuning of software and hardware elements, and is a constant focus
for improvement by vendors and operators alike. The introduction
of new security mechanisms affects this performance balance. The
performance impact of any incremental step of security improvement
will need to be weighed by the community, and introduced in such a
way that allows the vendor and operator community a path to
adoption that upholds reasonable performance metrics. Therefore,
certain specification elements may be introduced carrying the
"SHOULD" guidance, with the intention that the same mechanism will
carry a "MUST" in the next release of the specification. This
gives the vendors and implementors the guidance they need to tune
their software and hardware appropriately over time. Last, some
security mechanisms require the build out of other operational
support systems, and this will take time. An example where these
three reasons are at play in an incremental improvement roadmap is
seen in the improvement of BGP's [RFC4271] security via the update
of the TCP Authentication Option (TCP-AO)
[I-D.ietf-tcpm-tcp-auth-opt] effort. It would be ideal, and
reflect best common security practice, to have a fully specified
key management protocol for negotiating TCP-AO's authentication
material, using certificates for peer authentication in the
keying. However, in the spirit of incremental deployment, we will
first address issues like cryptographic algorithm agility, replay
attacks, TCP session resetting in the base TCP-AO protocol before
we layer key management on top of it.
3. The deploy-ability of the improved security solutions on currently
running routing infrastructure equipment. This begs the
consideration of the current state of processing power available
on routers in the network today.
4. Operational deploy-ability - A solutions acceptability will also
be measured by how deployable the solution is by common operator
teams using common deployment processes and infrastructures. I.e.
We will try to make these solutions fit as well as possible into
current operational practices or router deployment. This will be
heavily influenced by operator input, to ensure that what we
specify can -- and, more importantly, will -- be deployed once
specified and implemented by vendors. Deployment of incrementally
more secure routing infrastructure in the Internet is the final
measure of success. Measurably, we would like to see an increase
in the number of surveyed respondents who report deploying the
updated authentication mechanisms anywhere across their network,
as well as a sharp rise in usage for the total percentage of their
network's routers.
Lebovitz & Expires May 9, 2010 [Page 9]
Internet-Draft KARP Roadmap November 2009
Interviews with operators show several points about routing
security. First, over 70% of operators have deployed transport
connection protection via TCP-MD5 on their EBGP [ISR2008] . Over
55% also deploy MD5 on their IBGP connections, and 50% deploy MD5
on some other IGP. The survey states that "a considerable
increase was observed over previous editions of the survey for use
of TCP MD5 with external peers (eBGP), internal peers (iBGP) and
MD5 extensions for IGPs." Though the data is not captured in the
report, the authors believe anecdotally that of those who have
deployed MD5 somewhere in their network, only about 25-30% of the
routers in their network are deployed with the authentication
enabled. None report using IPsec to protect the routing protocol,
and this was a decline from the few that reported doing so in the
previous year's report.
From my personal conversations with operators, of those using MD5,
almost all report deploying with one single manual key throughout
the entire network. These same operators report that the one
single key has not been changed since it was originally installed,
sometimes five or more years ago. When asked why, particularly
for the case of BGP using TCP MD5, the following reasons are often
given:
A. Changing the keys triggers a TCP reset, and thus bounces the
links/adjacencies, undermining Service Level Agreements
(SLAs).
B. For external peers, difficulty of coordination with the other
organization is an issue. Once they find the correct contact
at the other organization (not always so easy), the
coordination function is serialized and on a per peer/AS
basis. The coordination is very cumbersome and tedious to
execute in practice.
C. Keys must be changed at precisely the same time, or at least
within 60 seconds (as supported by two major vendors) in order
to limit connectivity outage duration. This is incredibly
difficult to do, operationally, especially between different
organizations.
D. Relatively low priority compared to other operatoinal issues.
E. Lack of staff to implement the changes device by device.
F. There are three use cases for operational peering at play
here: peers and interconnection with other operators, Internal
BGP and other routing sessions within a single operator, and
operator-to-customer-CPE devices. All three have very
different properties, and all are reported as cumbersome. One
operator reported that the same key is used for all customer
premise equipment. The same operator reported that if the
customer mandated, a unique key could be created, although the
Lebovitz & Expires May 9, 2010 [Page 10]
Internet-Draft KARP Roadmap November 2009
last time this occurred it created such an operational
headache that the administrators now usually tell customers
that the option doesn't even exist, to avoid the difficulties.
These customer-uniqe keys are never changed, unless the
customer demands so.
The main threat at play here is that a terminated employee from
such an operator who had access to the one (or few) keys used for
authentication in these environments could easily wage an attack
-- or offer the keys to others who would wage the attack -- and
bring down many of the adjacencies, causing destabilization to the
routing system.
Whatever mechanisms we specify need to be easier than the current
methods to deploy, and should provide obvious operational
efficiency gains along with significantly better security and
threat protection. This combination of value may be enough to
drive much broader adoption.
5. Address the threats enumerated above in the "Threats" section
(Section 2) for each routing protocol, along a roadmap. Not all
threats may be able to be addressed in the first specification
update for any one protocol. Roadmaps will be defined so that
both the security area and the routing area agree on how the
threats will be addressed completely over time.
6. Create a re-usable architecture, framework, and guidelines for
various IETF working teams who will address these security
improvements for various Routing Protocols. The crux of the KARP
work is to re-use that framework as much as possible across
relevant Routing Protocols. For example, designers should aim to
re-use the key management protocol that will be defined for BGP's
TCP-AO key establishment for as many other routing protocols as
possible. This is but one example.
7. Bridge any gaps between IETF's Routing and Security Areas by
recording agreements on work items, roadmaps, and guidance from
the Area leads and Internet Architecture Board (IAB, www.iab.org).
1.5. Non-Goals
The following two goals are considered out-of-scope for this effort:
o Privacy of the packets on the wire, at this point in time. Once
this roadmap is realized, we may revisit work on privacy.
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o Message content security. This work is being addressed in other
IETF efforts, like SIDR.
1.6. Audience
The audience for this roadmap includes:
o Routing Area working group chairs and participants - These
people are charged with updates to the Routing Protocol
specifications. Any and all cryptographic authentication work
on these specifications will occur in Routing Area working
groups, with close partnership with the Security Area. Co-
advisors from Security Area may often be named for these
partnership efforts.
o Security Area reviewers of routing area documents - These people
are delegated by the Security Area Directors to perform reviews
on routing protocol specifications as they pass through working
group last call or IESG review. They will pay particular
attention to the use of cryptographic authentication and
corresponding security mechanisms for the routing protocols.
They will ensure that incremental security improvements are
being made, in line with this roadmap.
o Security Area engineers - These people partner with routing area
authors/designers on the security mechanisms in routing protocol
specifications. Some of these security area engineers will be
assigned by the Security Area Directors, while others will be
interested parties in the relevant working groups.
o Operators - The operators are a key audience for this work, as
the work is considered to have succeeded if the operators deploy
the technology, presumably due to a perception of significantly
improved security value coupled with relative similarity to
deployment complexity and cost. Conversely, the work will be
considered a failure if the operators do not care to deploy it,
either due to lack of value or perceived (or real) over-
complexity of operations. And as such, the GROW and OPSEC WGs
should be kept squarely in the loop as well.
2. Threats
In RFC4949[RFC4949], a threat is defined as a potential for violation
of security, which exists when there is a circumstance, capability,
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action, or event that could breach security and cause harm. This
section defines the threats that are in scope for this roadmap, and
those that are explicitly out of scope. This document leverages the
"Generic Threats to Routing Protocols" model, RFC 4593 [RFC4593] ,
capitalizes terms from that document, and offers a terse definition
of those terms. (More thorough description of routing protocol
threats sources, motivations, consequences and actions can be found
in RFC 4593 [RFC4593] itself). The threat listings below expand upon
these threat definitions.
2.1. Threats In Scope
The threats that will be addressed in this roadmap are those from
OUTSIDERS, attackers that may reside anywhere in the Internet, have
the ability to send IP traffic to the router, may be able to observe
the router's replies, and may even control the path for a legitimate
peer's traffic. These are not legitimate participants in the routing
protocol. Message authentication and integrity protection
specifically aims to identify messages originating from OUTSIDERS.
The concept of OUTSIDERS can be further refined to include attackers
who are terminated employees, and those sitting on-path.
o On-Path - attackers with control of a network resource or a tap
along the path of packets between two routers. An on-path
outsider can attempt a man-in-the-middle attack, in addition to
several other attack classes. A man-in-the-middle (MitM) attack
occurs when an attacker who has access to packets flowing between
two peers tampers with those packets in such a way that both peers
think they are talking to each other directly, when in fact they
are actually talking to the attacker only. Protocols conforming
to this roadmap will use cryptographic mechanisms to prevent a
man-in-the-middle attacker from situating himself undetected.
o Terminated Employees - in this context, those who had access
router configuration that included keys or keying material like
pre-shared keys used in securing the routing protocol. Using this
material, the attacker could send properly MAC'd spoofed packets
appearing to come from router A to router B, and thus impersonate
an authorized peer. The attacker could then send false traffic
that changes the network behavior from its operator's design. The
goal of addressing this source specifically is to call out the
case where new keys or keying material becomes necessary very
quickly, with little operational expense, upon the termination of
such an employee. This grouping could also refer to any attacker
who somehow managed to gain access to keying material, and said
access had been detected by the operators such that the operators
have an opportunity to move to new keys in order to prevent an
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attack.
These ATTACK ACTIONS are in scope for this roadmap:
o SPOOFING - when an unauthorized device assumes the identity of an
authorized one. Spoofing can be used, for example, to inject
malicious routing information that causes the disruption of
network services. Spoofing can also be used to cause a neighbor
relationship to form that subsequently denies the formation of the
relationship with the legitimate router.
o FALSIFICATION - an action whereby an attacker sends false routing
information. To falsify the routing information, an attacker has
to be either the originator or a forwarder of the routing
information. Falsification may occur by an ORIGINATOR, or a
FORWARDER, and may involve OVERCLAIMING, MISCLAIMING, or
MISTATEMENT of network resource reachability. We must be careful
to remember that in this work we are only targeting falsification
from outsiders as may occur from tampering with packets in flight.
Falsification from BYZANTINES (see the Threats Out of Scope
section (Section 2.2) below) are not addressed by the KARP effort.
o INTERFERENCE - when an attacker inhibits the exchanges by
legitimate routers. The types of interference addressed by this
work include:
* ADDING NOISE
* REPLAYING OUT-DATED PACKETS
* INSERTING MESSAGES
* CORRUPTING MESSAGES
* BREAKING SYNCHRONIZATION
* Changing message content
o DoS attacks on transport sub-systems - This includes any other DoS
attacks specifically based on the above attack types. This is
when an attacker sends spoofed packets aimed at halting or
preventing the underlying protocol over which the routing protocol
runs, for example halting a BGP session by sending a TCP FIN or
RST packet. Since this attack depends on spoofing, operators are
encouraged to deploy
o DoS attacks using the authentication mechanism - This includes an
attacker sending packets which confuse or overwhelm a security
mechanism itself. An example is initiating an overwhelming load
of spoofed authenticated route messages so that the receiver needs
to process the MAC check, only to discard the packet, sending CPU
levels rising. Another example is when an attacker sends an
overwhelming load of keying protocol initiations from bogus
sources. All other possible DoS attacks are out of scope (see
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next section).
o Brute Foce Attacks Against Password/Keys - This includes either
online or offline attacks where attempts are made repeatedly using
different keys/passwords until a match is found. While it is
impossible to make brute force attacks on keys completely
unsuccessful, proper design can make such attacks much harder to
succeed. For exmaple, the key length should be sufficiently long
so that covering the entire space of possible keys is improbable
using computational power expected to be available 10 years out or
more. Also, frequently changing the keys may render useless a
successful guess some time in the future, as those keys may no
longer be in use.
2.2. Threats Out of Scope
Threats from BYZANTINE sources -- faulty, misconfigured, or subverted
routers, i.e., legitimate participants in the routing protocol -- are
out of scope for this roadmap. Any of the attacks described in the
above section (Section 2.1) that may be levied by a BYZANTINE source
are therefore also out of scope.
In addition, these other attack actions are out of scope for this
work:
o SNIFFING - passive observation of route message contents in flight
o FALSIFICATION by BYZANTINE sources - unauthorized message content
by a legitimate authorized source.
o INTERFERENCE due to:
* NOT FORWARDING PACKETS - cannot be prevented with cryptographic
authentication
* DELAYING MESSAGES - cannot be prevented with cryptographic
authentication
* DENIAL OF RECEIPT - cannot be prevented with cryptographic
authentication
* UNAUTHORIZED MESSAGE CONTENT - the work of the IETF's SIDR
working group
(http://www.ietf.org/html.charters/sidr-charter.html).
* Any other type of DoS attack. For example, a flood of traffic
that fills the link ahead of the router, so that the router is
rendered unusable and unreachable by valid packets is NOT an
attack that this work will address. Many other such examples
could be contrived.
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3. Categorizing Routing Protocols
For the purpose of this security roadmap definition, we will
categorize the routing protocols into groups and have design teams
focus on the specification work within those groupings. It is
believed that the groupings will have like requirements for their
authentication mechanisms, and that reuse of authentication
mechanisms will be greatest within these grouping. The work items
placed on the roadmap will be defined and assigned based on these
categorizations. It is also hoped that, down the road in the Phase 2
work, we can create one KMP per category (if not for several
categories) so that the work can be easily leveraged by the various
Routing Protocol teams. KMPs are useful for allowing simple,
automated updates of the traffic keys used in a base protocol. KMPs
replace the need for humans, or OSS routines, to periodically replace
keys on running systems. It also removes the need for a chain of
manual keys to be chosen or configured. When configured properly, a
KMP will enforce the key freshness policy of two peers by keeping
track of the key lifetime and negotiating a new key at the defined
interval.
3.1. Category: Messaging Transaction Type
The first categorization defines four types of messaging transactions
used on the wire by the base Routing Protocol. They are:
One-to-One One peer router directly and intentionally delivers a
route update specifically to one other peer router.
Examples are BGP and LDP. Point-to-point modes of
both IS-IS and OSPF, when sent over both traditional
point-to-point links and when using multi-access
layers, may both also fall into this category.
[question to reviewers: Should we list all protocols
into these categories right here, or just give a few
examples?]
One-to-Many A router peers with multiple other routers on a single
network segment -- i.e. on link local -- such that it
creates and sends one route update message which is
intended for consumption by multiple peers. Examples
would be OSPF and IS-IS in their broadcast, non-point-
to-point modes.
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Client-Server A client-server routing protocol is one where one
router initiates a request for route information from
another router, who then formulates a response to that
request, and replies with the requested data.
Examples are a BGP Route Reflector and [???? Are
there other examples? Is this the right example? Do
discovery protocols fall under this category?].
Multicast Multicast protocols have unique security properties
because of the fact that they are inherently group-
based protocols and thus have group keying
requirements at the routing level where link-local
routing messages are multicasted. Also, at least in
the case of PIM-SM, some messages are are sent unicast
to a given peer(s), as is the case with router-close-
to-sender and the "Rendezvous Point". Some work for
application layer message security has been done in
the Multicast Security working group (MSEC,
http://www.ietf.org/html.charters/msec-charter.html)
and may be helpful to review, but is not directly
applicable.
[author's note: I think the above definitions need clean up. Routing
area folks, especially ADs, PLEASE suggest new text.]
3.2. Category: Peer vs. Group Keying
The second axis of categorization groups protocols by the keying
mechanism that will be necessary for distributing session keys to the
actual Routing Protocol transports. They are:
Peer keying One router sends the keying messages directly and only
to one other router, such that a one-to-one, unique
keying security association (SA) is established
between the two routers
Group Keying One router creates and distributes a single keying
message to multiple peers. In this case an group SA
will be established and used between multiple peers
simultaneously. Group keying exists for protocols
like OSPF [RFC2328] , and also for multicast protocols
like PIM-SM [RFC4601].
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3.3. Category: Update vs. Discovery Protocol
The third category group considers protocols by the contents of the
messages being exchanged in the Routing Protocol. They are:
Updates Messages that carry route advertisements or update
information from peer to peer
Discovery Messages sent as part of a policy, peer, or service
discovery process. These messages are normally
exchanged prior to any adjacency being formed, and
before any updates are sent. For example, end-point
discovery mechanisms are common in L2VPN and L3VPN
solutions.
[QUESTION TO REVIEWERS: is this really just what's described in 3.1
as "Client-Server" and/or "One-to-One"? Is there really such a
different in discovery protocols that they need their own category to
figure out how to authenticate them? Can someone provide a few
examples?
3.4. Security Characterization Vectors
A few more considerations must be made about the protocol and its use
when initially categorizing the protocol and scoping the
authentication work.
3.4.1. Internal vs. External Operation
The designers must consider whether the protocol is an internal
routing protocol or an external one, i.e. Does it primarily run
between peers within a single domain of control or between two
different domains of control? Some protocols may be used in both
cases, internally and externally, and as such various modes of
authentication operation may be required for the same protocol.
While it is preferred that all routing exchanges run with the utmost
security mechanisms enabled in all deployments, this exhortation is
greater for those protocols running on inter-domain point-to-point
links, and greatest for those on shared access link layers with
several different domains interchanging together, because the volume
of attackers are greater from the outside. Note however that the
consequences of internal attacks maybe no less severe -- in fact they
may be quite a bit more severe -- than an external attack. An
example of this internal versus external consideration is BGP which
has both EBGP and IBGP modes. Another example is a multicast
protocol where the neighbors are sometimes within a domain of control
and sometimes at an inter-domain exchange point. In the case of
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PIM-SM running on an internal multi-access link, It would be
acceptable to give up some security to get some convenience by using
a group key between the peers on the link. On the other hand, in the
case of PIM-SM running over a multi-access link at a public exchange
point, operators may favor security over convenience by using unique
pair-wise keys for every peer. Designers must consider both modes of
operation and ensure the authentication mechanisms fit both.
Operators are encouraged to run cryptographic authentication on all
their adjacencies, but to work from the outside in, i.e. The EBGP
links are a higher priority than the IBGP links because they are
externally facing, and, as a result, more likely to be targeted in an
attack.
3.4.2. Unique versus Shared Keys
This section discusses security considerations regarding when it is
appropriate to use the same authentication key inputs for multiple
peers and when it is not. This is largely a debate of convenience
versus security. It is often the case that the best secured
mechanism is also the least convenient mechanism. For example, an
air gap between a host and the network absolutely prevents remote
attacks on the host, but having to copy and carry files using the
"sneaker net" is quite inconvenient and unscalable.
Operators have erred on the side of convenience when it comes to
securing routing protocols with cryptographic authentication. Many
do not use it at all. Some use it only on external links, but not on
internal links. Those that do use it often use the same key for all
peers across their entire network. It is common to see the same key
in use for years, and that being the same key that was entered when
authentication was originally configured, or the routing gear
deployed.
The goal for designers is to create authentication mechanisms that
are easy for the operators to deploy and manage, and still use unique
keys between peers (or small groups on multi-access links), and
within between sessions. Operators have the impression that they
NEED one key shared across the network, when in fact they do not.
What they need is the relative convenience they experience from
deploying cryptographic authentication with one (or few) key,
compared to the inconvenience they would experience if they deployed
the same authentication mechanism using unique pair-wise keys. An
example is BGP Route Reflectors. Here operators often use the same
authentication key between each client and the route reflector. The
roadmaps defined from this guidance document will allow for unique
keys to be used between each client and the peer, without sacrificing
much convenience. Designers should strive to deliver peer-wise
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unique keying mechanisms with similar ease-of-deployment properties
as today's one-key method.
Operators must understand the consequences of using the same keys
across many peers. Unique keys are more secure than shared keys
because they reduce both the attack target size and the attack
consequence size. In this context, the attack target size represents
the number of unique routing exchanges across a network that an
attacker may be able to observe in order to gain security association
credentials, i.e. crack the keys. If a shared key is used across the
entire internal domain of control, then the attack target size is
very large. The larger the attack target, the easier it is for the
attacker to gain access to analysis data, and greater the volume of
analysis data he can access in a given time frame, both of which make
his job easier. Using the same key across the network makes the
attack vulnerability surface more penetrable than unique keys.
Consider also the attack consequence size, the amount of routing
adjacencies that can be negatively affected once a breach has
occurred, i.e. once the keys have been acquired by the attacker.
Again, if a shared key is used across the internal domain, then the
consequence size is the whole network. Ideally, unique key pairs
would be used for each adjacency.
In some cases designers may need to use shared keys in order to solve
the given problem space. For example, a multicast packet is sent
once but then observed and consumed by several routing neighbors. If
unique keys were used per neighbor, the benefit of multicast would be
erased because the casting peer would have to create a different
announcement packet/stream for each listening peer. Though this may
be desired and acceptable in some small amount of use cases, it is
not the norm. Shared group keys are an acceptable solution here, and
much work has been done already in this area (see MSEC working
group).
3.4.3. Out-of-Band vs. In-line Key Management
This section discusses the security and use case considerations for
keys placed on devices through out-of-band configurations versus
through one routing peer-to-peer key management protocol exchanges.
Note, when we say here "Peer-to-Peer KMP" we do not mean in-band to
the Routing Protocol. Instead, we mean that the exchange occurs in-
line, over IP, between the two routing peers directly. In in-line
KMP the peers themselves handle the key and security association
negotiation between themselves directly, whereas in an out-of-band
system the keys are placed onto the device through some other
configuration or management method or interface.
An example of an out-of-band mechanism could be an administrator who
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makes a remote management connection (e.g. using SSH) to a router and
manually enters the keying information -- like the algorithm, the
key(s), the lifetimes, etc. Another example could be an OSS system
which inputs the same information via a script over an SSH
connection, or by pushing configuration through some other management
connection, standard (Netconf-based) or proprietary.
The drawbacks of an out-of-band mechanism include: lack of scale-
ability, complexity and speed of changing if a breach is suspected.
For example, if an employee who had access to keys was was
terminated, or if a machine holding those keys was belived
compromised, then the system would be considered insecure and
vulnerable until new keys were defined by a human. Those keys then
need to be placed into the OSS system, manually, and the OSS system
then needs to push the change -- often during a very limited change
window -- into the relevant devices. If there are multiple
organizations involved in these connections, this process is greatly
complicated.
The benefits of out-of-band mechanism is that once the new keys/
parameters are set in OSS system they can be pushed automatically to
all devices within the OSS's domain of control. Operators have
mechanisms in place for this already. In small environments with few
routers, a manual system is not difficult to employ.
We further define an in-line key exchange as using cryptographicly
protected identity verification, session key negotiation, and
security association parameter negotiation between the two routing
peers. The KMP between the two peers may also include the
negotiation of parameters, like algorithms, cryptographic inputs
(e.g. initialization vectors), key life-times, etc.
The benefits an in-line KMP are several. An in-line KMP results in
key(s) that are privately generated, and not recorded permanently
anywhere. Since the traffic keys used in a particular connection are
not a fixed part of a device configuration no steal-able data exists
anywhere else in the operator's systems which can be stolen, e.g. in
the case of a terminated or turned employee. If a server or other
data store is stolen or compromised, the thieves gain no access to
current traffic keys. They may gain access to key derivation
material, like a PSK, but not current traffic keys in use. In this
example, these PSKs can be updated into the device configurations
(either manually or through an OSS) without bouncing or impacting the
existing session at all. In the case of using raw assymetric keys or
certificates, instead of PSKs, the data theft would likely not even
result in any compromise, as the key pairs would have been generated
on the routers, and never leave those routers. In such a case no
changes are needed on the routers; the connections will continue to
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be secure, uncompromised. Additionally, with a KMP regular re-keys
operations occur without any operator involvement or oversight. This
keeps keys fresh.
The drawbacks to using a KMP are few. First, a KMP requires more
cryptographic processing for the router at the very beginning of a
connection. This will add some minor start-up time to connection
establishment versus a purely manual key approach. Once a connection
with traffic keys have been established via a KMP, the performance is
the same in the KMP and the out-of-band case. KMPs also add another
layer of protocol and configuration complexity which can fail or be
misconfigured. This was more of an issue when these KMPs were first
deployed, but less so as these implementaitons and operational
experience with them has matured.
The desired end goal is in-line KMPs.
4. The Roadmap
4.1. Work Phases on any Particular Protocol
The desired endstate for the KARP work contains several items.
First, the people desiring to deploy securely authenticated and
integrity validated packets between routing peers have the tools
specified, implemented and shipping in order to deploy. These tools
should be fairly simple to implement, and not more complex than the
security mechanisms to which the operators are already accustomed.
(Examples of security mechanisms to which router operators are
accustomed include: the use of assymetric keys for authentication in
SSH for router configuration, the use of pre-shared keys (PSKs) in
TCP MD5 for BGP protection, the use of self-signed certificates for
HTTPS access to device Web-based user interfaces, the use of strongly
constructed passwords and/or identity tokens for user identification
when logging into routers and management systems.) While the tools
that we intend to specify may not be able to stop a deployment from
using "foobar" as an input key for every device across their entire
routing domain, we intend to make a solid, modern security system
that is not too much more difficult than that. In other words,
simplicity and deployability are keys to success. The Routing
Protocols will specify modern cryptographic algorithms and security
mechanisms. Routing peers will be able to employ unique, pair-wise
keys per peering instance, with reasonable key lifetimes, and
updating those keys on a somewhat regular basis will be operationally
easy, causing no service interruption.
Achieving the above described end-state using manual keys may only be
pragmatic in very small deployments. In larger deployments, this end
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state will be much more operationally difficult to reach with only
manual keys. Thus, there will be a need for key life cycle
management, in the form of a key management protocol, or KMP. We
expect that the two forms, manual key usage and KMP usage, will co-
exist in the real world. For example, a provider's edge router at a
public exchange peering point will want to use a KMP for ensuring
unique and fresh keys with external peers, while a manual key may be
used between a provider's access edge router and each of the same
provider's customer premise routers with which it peers.
In accordance with the desired end state just described, we define
two main work phases for each Routing Protocol:
1. Enhance the Routing Protocol's current authentication mechanism.
This work involves enhancing a Routing Protocol's current
security mechanisms in order to achieve a consistent, modern
level of security functionality within its existing keying
framework. It is understood and accepted that the existing
keying frameworks are largely based on manual keys. Since many
operators have already built operational support systems (OSS)
around these manual key implementations, there is some automation
available for an operator to leverage in that way, if the
underlying mechanisms are themselves secure. In this phase, we
explicitly exclude embedding or creating a KMP. A list of the
requirements for Phase 1 work are below in the section
"Requirements for Phase 1 Routing Protocols' Security Updates
(Section 4.2).
2. Develop an automated keying framework. The second phase will
focus on the development of an automated keying framework to
faciliate unique pair-wise (or perhaps group-wise, where
applicable) keys per peering instance. This involves the use of
a KMP. A KMP is helpful because it negotiates unique, pair wise,
random keys without administrator involvement. It also
negotiates several of the SA parameters required for the secure
connection, including key life times. It keeps track of those
lifetimes using counters, and negotiates new keys and parameters
before they expire, again, without administrator interaction.
Additionally, in the event of a breach, changing the KMP key will
immediately cause a rekey to occur for the Traffic Key, and those
new Traffic Keys will be installed and used in the current
connection. In summary, a KMP provides a protected channel
between the peers through which they can negotiate and pass
important data required to exchange proof of key identifiers,
derive Traffic Keys, determine re-keying, synchronize their
keying state, signal various keying events, notify with error
messages, etc. To address brute force attacks [RFC3562]
recommends a key management practice to minimize the possibility
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of successful attack-- frequent key rotation, limited key
sharing, key length restrictions, etc. Advances in computational
power due to Moore's law are making that management burden
untenable-- keys must be of a size and composition that makes
configuration and maintance difficult or keys must be rotated
with an unreasonable frequency. A KMP will help immensely with
this growing problem.
The framework for any one Routing Protocol will fall under, and
be able to leverage, the generic framework described below in
section Section 4.3.
4.2. Requirements for Phase 1 Routing Protocols' Security Update
Here is a proposed list of requirements that SHOULD be addressed by
Phase 1 (according to "1." above) security updates to Routing
Protocols [to be reviewed after -01 is released]:
1. Clear definitions of which elements of the transmission (frame,
packet, segment, etc.) are protected by the authentication
mechanism
2. Strong algorithms, and defined and accepted by the security
community, MUST be specified. The option should use algorithms
considered accepted by the security community, which are
considered appropriately safe. The use of non-standard or
unpublished algorithms SHOULD BE avoided.
3. Algorithm agility for the cryptograhpic algorithms used in the
authentication MUST be specified, i.e. more than one algorithm
MUST be specified and it MUST be clear how new algorithms MAY be
specified and used within the protocol. This requirement exists
in case one algorithm gets broken suddenly. Research to
identify weakness in algorithms is constant. Breaking a cipher
isn't a matter of if, but when it will occur. t's highly
unlikely that two different algorithms will be broken
simultaneously. So, if two are supported, and one gets broken,
we can use the other until we get a new one in place. Having
the ability within the protocol specification to support such an
event, having algorithm agility, is essential. Mandating two
algorithms provides both a redundancy, and a mechanism for
enacting that redundancy when needed.
4. Secure use of simple PSKs, offering both operational convenience
as well as building something of a fence around stupidity, MUST
be specified.
5. Inter-connection replay protection. Packets captured from one
connection MUST NOT be able to be re-sent and accepted during a
later connection.
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6. Intra-connection replay protection. Packets captured during a
connection MUST NOT be able to be re-sent and accepted during
that same connection, to deal with long-lived connections.
7. A change of security parameters REQUIRES, and even forces, a
change of session traffic keys
8. Intra-connection re-keying which occurs without a break or
interruption to the current peering session, and, if possible,
without data loss, MUST be specified.
9. Efficient re-keying SHOULD be provided. The specificaion SHOULD
support rekeying during a connection without the need to expend
undue computational resources. In particular, the specification
SHOULD avoid the need to try/compute multiple keys on a given
packet.
10. Prevent DoS attacks as those described as in-scope in the
threats section Section 2.1 above.
11. Default mechanisms and algorithms specified and defined as
REQUIRED for all implementations
12. Manual keying MUST be supported.
13. Convergence times of the Routing Protocols SHOULD NOT be
materially affected. Materially here is defined as anything
greater than a 5% convergence time increase. Note that
convergence is different than boot time. Also note that
convergence time has a lot to do with the speed of processors
used on individual routing peers, and this increases by Moore's
law over time. Therefore, this requirement should be considered
only in terms of total number of messages that must be
exchanged, and less for the computational intensity of
processing any one message.
14. The changes or addition of security mechanisms SHOULD NOT cause
a refresh of route updates or cause additional route updates to
be generated
15. Architecture of the specification MUST consider and allow for
future use of a KMP.
4.3. Common Framework
Each of the categories of routing protocols above will require unique
designs for authenticating and integrity checking their protocols.
However, a single underlying framework for delivering automatic
keying to those solutions will be pursued. Providing such a single
framework will significantly reduce the complexity of each step of
the overall roadmap. For example, if each Routing Protocol needed to
define it's own key management protocol this would balloon the total
amount of different sockets that are needed to be opened and
processes that are needed to be simultaneously running on an
implementation. It would also significantly increase the run-time
complexity and memory requirements of such systems running multiple
Routing Protocols, causing perhaps slower performance of such
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systems. However, if we can land on a very small set (perhaps one or
two) of automatic key management protocols, KMPs, that the various
Routing Protocols can use, then we can reduce this implementation and
run-time complexity. We can also decrease the total amount of time
implementers need to deliver the KMPs for the Routing Protocols that
will provide better threat protection.
The components for the framework are listed here, and described
below:
o Routing Protocol security mechanism
o KMP
o KeyStore
o Traffic Key
o RoutingProtocol-to-KMP API
o RoutingProtocol-to-KeyStore API
o KMP-to-KeyStore API
o Common Routing Protocol mechanisms
o Identifiers
o Proof of identity
o Profiles
The framework is modularized for how keys and security association
(SA) parameters generally get passed from a KMP to a transport
protocol. It contains three main blocks and APIs.
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+------------+ +--------------------+
| | | | Check +-----------+
| Identifier +-->| +---------->| |
| | | KMP Function | | Identity |
+----------- + | |<----------+ Proof |
| | Approve | |
+-+--------------+---+ +-----------+
| |
KMP-to-KeyStore | |
API | |
\|/ |
+-------+-------+ |
| | | KMP-to-RoutingProtocol
| | | API
| KeyStore | |
| | |
+-------+-------+ |
| |
| |
KeyStore-to- | |
RoutingProtocol API | |
| \|/
+--------------------------+-------------+
| | |
| \|/ Common RtgProto |
| +-------+-------+ Authentication |
| | | Mechanisms |
+---| Traffic |-----+--------------+
| | Key(s) | |
| | | |
| +---------------+ Specific |
| RoutingProtocol |
| Authentication |
| Security |
| Mechanism |
+----------------------------------------+
Figure 1: Automatic Key Management Framework
Each element of the framework is described here:
o Routing Protocol - Routing protocol security mechanism - In each
case, the Routing Protocol will contain a mechanism for using
session keys in their security option. When the Routing
Protocol uses a transport substrate, e.g. the way BGP, LDP
and MSDP use TCP, then this applies to the security mechanism
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the includes that substrate.
o KeyStore - Each implementation will also contain a protocol
independent mechanism for storing keys, called KeyStore. The
KeyStore will have multiple different logical containers, one
container for each session key that any given Routing
Protocol will need. Keys stored here may be a Peer Key or a
Traffic Key. There may also be associated parameters as
required by the SA for any given Routing Protocol.
o Peer Key A key used between peers from which a traffic key is
derived. An example is a PSK.
o Traffic Key The actual key used on each packet of a message.
This key may be derived from the key existing in the
KeyStore. This will depend on whether the key in KeyStore
was a manual PSK for the peers, or whether a connection-aware
KMP created the key. Further, it will be connection
specific, so as to provide inter- and intra-connection replay
protection.
o RoutingProtocol-KeyStore API - There will be an API for Routing
Protocol to retrieve (or receive; it could be a push or a
pull) the keys from the KeyStore. This will enable
implementers to reuse the same API calls for all their
Routing Protocols. The API will necessarily include facility
to retrieve other SA parameters required for the construction
of the Routing Protocol's packets, like key IDs or key
lifetimes, etc.
o KMP - There will be an automated key management protocol, KMP.
This KMP will run between the peers. The KMP serves as a
protected channel between the peers, through which they can
negotiate and pass important data required to exchange proof
of key identifiers, derive session keys, determine re-keying,
synchronize their keying state, signal various keying events,
notify with error messages, etc. As an analogy, in the IPsec
protocol (RFC4301 [RFC4301], RFC4303 [RFC4303] and RFC4306
[RFC4306]) IKEv2 is the KMP that runs between the two peers,
while AH and ESP are two different base protocols that take
session keys from IKEv2 and use them in their transmissions.
In the analogy, the Routing Protocol, say BGP and LDP, are
analogous to ESP and AH, while the KMP is analogous to IKEv2
itself.
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o RoutingProtocol-KMP API - There will be an API for the Routing
Protocol to request a session key of the KMP, and be notified
when the keys are available for it. The API will also
contain a mechanism for the KMP to notify the Routing
Protocol that there are new keys that it must now use, even
if it didn't request those keys. The API will also include a
mechanism for the KMP to receive requests for session keys
and other parameters from the routing protocol. The KMP will
also be aware of the various Routing Protocols and each of
their unique parameters that need to be negotiated and
returned.
o KMP-KeyStore API - There will be an API for the KMP to place
keys and parameters into the KeyStore after their negotiation
and derivation with the other peer. This will enable the
implementers to reuse the same calls for multiple KMPs that
may be needed to address the various categories of Routing
Protocols as described in the section definingcategories
(Section 3).
[after writing this all up, I'm not sure we really need the key_store
in the middle. As long as we standardize fully all the calls needed
from any Routing Protocol to any KMP, then there can be a generic
hand-down function from the KMP to the Routing Protocol when the key
and parameters are ready. Let's sleep on it.]
[will need state machines and function calls for these APIs, as one
of the work items. In essence, there is a need for a core team to
develop the APIs out completely in order for the Routing Protocol
teams to use them. Need to get this team going asap.]
o Identifiers - A KMP is fed by identities. The identities are
text strings used by the peers to indicate to each other that
each are known to the other, and authorized to establish
connections. Those identities must be represented in some
standard string format, e.g. an IP address -- either v4 or
v6, an FQDN, an RFC 822 email address, a Common Name [RFC
PKI], etc. Note that even though routers do not normally
have email addresses, one could use an RFC 822 email address
string as a formatted identifier for a router. They would do
so simply by putting the router's reference number or name-
code as the "NAME" part of the address, left of the "@"
symbol. They would then place some locational context in the
"DOMAIN" part of the string, right of the "@" symbol. An
example would be "rtr0210@sf.ca.us.company.com". This
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document does not suggest this string value at all. Instead,
the concept is used only to clarify that the type of string
employed does not matter. It also does not matter what
specific text you chose to place in that string type. It
only matters that the type of string -- and it's format --
must be agreed upon by the two endpoints. Further, the
string can be used as an identifier in this context, even if
the string is not actually provisioned in it's source domain.
For example, the email address "rtr0210@sf.ca.us.company.com"
may not actually exist as an email address in that domain,
but that string of characters may still be used as an
identifier type(s) in the routing protocol security context.
What is important is that the community decide on a small but
flexible set of Identifiers they will all support, and that
they decide on the exact format of those string. The formats
that will be used must be standardized and must be sensible
for the routing infrastructure.
o Identity Proof - Once the form of identity is decided, then
there must be a cryptographic proof of that identity, that
the peer really is who they assert themselves to be. Proof
of identity can be arranged between the peers in a few ways,
for example pre-shared keys, raw assymetric keys, or a more
user-friendly representation of assymetric keys, like a
certificate. Certificates can be used in a way requiring no
additional supporting systems -- e.g. public keys for each
peer can be maintained locally for verification upon contact.
Certificate management can be made more simple and scalable
with the use minor additional supporting systems, as is the
case with self-signed certificates and a flat file list of
"approved thumbprints". Self-signed certificates will have
somewhat lower security properties than Certificate Authority
signed certificates [RFC Certs]. The use of these different
identity proofs vary in ease of deployment, ease of ongoing
management, startup effort, ongoing effort and management,
security strength, and consequences from loss of secrets from
one part of the system to the rest of the system. For
example, they differ in resistance to a security breach, and
the effort required to remediate the whole system in the
event of such a breach. The point here is that there are
options, many of which are quite simple to employ and deploy.
o Profiles - Once the KMP, Identifiers and Proofs mechanisms are
converged upon, they must be clearly profiled for each
Routing Protocol, so that implementors and deployers alike
understand the different pieces of the solution, and can have
similar configurations and interoperability across multiple
vendors' devices, so as to reduce management difficulty. The
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profiles SHOULD also provide guidance on when to use which
various combinations of options. This will, again, simplify
use and interoperability.
In addition to other business, administrative, and operational terms
they must already exchange prior to forming first adjacencies, it is
assumed that two parties deploying message authentication on their
routing protocol will also need to decide upon acceptable security
parameters for the connection. This will include the form and
content of the identity each use to represent the other. It will
also include the type of keys to be used, e.g. PSK, raw assymetric
keys, certificate. And it will include the acceptable cryptographic
algorithms, or algorithm suite. This agreement is necessary in order
for each to properly configure the connection on their respective
devices. The manner in which they agree upon and exchange this
policy information is normally via phone call or written exchange,
and is outside the scope of the KARP effort, but assumed to have
occured. We take as a given that each party knows the identity types
and values, key types and values, and acceptable cryptographic
algorithms for both their own device and the peer that form the
security policy for configuration on their device.
Common Mechanisms - In as much as they exist, the framework will
capture mechanisms that can be used commonly not only within a
particular category of Routing Protocol and Routing Protocol to KMP,
but also between Routing Protocol categories. Again, the goal here
is simplifying the implementations and runtime code and resource
requirements. There is also a goal here of favoring well vetted,
reviewed, operationally proven security mechanisms over newly brewed
mechanisms that are less well tried in the wild.
4.4. Work Items Per Routing Protocol
Each Routing Protocol will have a team (the [Routing_Protocol]-KARP
team) working on incrementally improving their Routing Protocol's
security, These teams will have the following main work items:
PHASE 1:
Characterize the RP
Assess the Routing Protocol to see what authentication mechanisms
it has today. Does it needs significant improvement to its
existing mechanisms or not? This will include determining if
modern, strong security algorithms and parameters are present.
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Define Optimal State
List the requirements for the Routing Protocol's session key usage
and format to contain to modern, strong security algorithms and
mechanisms, per the Requirements (Section 4.2) section above. The
goal here is to determine what is needed for they Routing Protocol
alone to be used securely with at least manual keys.
Gap Analysis
Enumerate the requirements for this protocol to move from its
current security state, the first bullet, to its optimal state, as
listed just above.
Transition and Deployment Considerations Document the operational
transition plan for moving from the old to the new security
mechanism. Will adjacencies need to bounce? What new elements/
servers/services in the infrastructure will be required? What is
an example work flow that an operator will take? The best
possible case is if the adjacency does not break, but this may not
always be possible.
Define, Assign, Design
Create a deliverables list of the design and specification work,
with milestones. Define owners. Release a document(s)
PHASE 2:
KMP Analysis
Review requirements for KMPs [RFC????]. Identify any nuances for
this particular protocol's needs and its use cases for KMP. List
the requirements that this Routing Protocol has for being able to
be use in conjunctions with a KMP. Define the optimal state.
Gap Analysis
Enumerate the requirements for this protocol to move from its
current security state to its optimal state.
Define, Assign, Design
Create a deliverabels list of the design and specification work,
with miletsones. Define owners. Do the design and document work
for a KMP to be able to generate the Routing Protocol's session
keys for the packets on the wire. These will be the arguments
passed in the API to the KMP in order to bootstrap the session
keys to the Routing Protocol.
There will also be a team formed to work on the base framework
mechanisms for each of the main categories, i.e. the blocks and API's
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represented in figure 1 (Figure 1).
4.5. Protocols in Categories
This section groups the Routing Protocols into like categories,
according to attributes set forth in Categories Section (Section 3).
Each group will have a design team tasked with improving the security
of the Routing Protocol mechanisms and defining the KMP requirements
for their group, then rolling both into a roadmap document upon which
they will execute.
BGP, LDP and MSDP
The Routing Protocol's that fall into the category of the one-to-
one peering messages, and will use peer keying protocols, AND are
all transmitted over TCP include BGP RFC 4271 [RFC4271], LDP
[RFC5036] and MSDP [RFC3618]. A team will work on one mechanism
to cover these three protocols. Much of the work on the Routing
Protocol update for its existing authentication mechanism is
already occuring in the TCPM Working Group, on the TCP-AO
[I-D.ietf-tcpm-tcp-auth-opt] document, as well as its
cryptography-helper document, TCP-AO-CRYPTO [I-D.ao-crypto]. The
exception is the mode where LDP is used directly on the LAN
[RFC????]. The work for this may go into the Group keying
category (w/ OSPF) mentioned below.
OSPF, ISIS, and RIP
The Routing Protocols that fall into the category Group keying
with one-to-many peering messages includes OSPF [RFC2328], ISIS
[RFC1195] and RIP [RFC2453]. Not surprisingly, all these routing
protocols have two other things in common. First, they are run
on a combination of the OSI datalink layer 2, and the OSI network
layer 3. By this we mean that they have a component of how the
routing protocol works which is specified in Layer 2 as well as
in Layer 3. Second, they are all internal gateway protocols, or
IGPs. The keying mechanisms and use will be much more
complicated to define for these than for a one-to-one messaging
protocol.
BFD
Because it is less of a routing protocol, per se, and more of a
peer aliveness detection mechanism, Bidirectional Forwarding
Detection (BFD) [RFC????] will have its own team.
RSVP [RFC????], RSVP-TE [RFC????], and PCE
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These three protocols will be handled together. [what more
characterisation should we give here? Routing AD's, provide text
pls?]
PIM-SM and PIM-DM
Finally, the multicast protocols of PIM-SM [RFC4601] and PIM-DM
[RFC3973] will be handled together. PIM-SM multicasts routing
information (Hello, Join/Prune, Assert) on a link-local basis,
using a defined multicast address. In addition, it specifies
unicast communication for exchange of information (Register,
Register-Stop) between the router closest to a group sender and
the "rendezvous point" (RP). The RP is typically not "on-link"
for a particular router. While much work has been done on
multicast security for application-layer groups, little has been
done to address the problem of managing hundreds or thousands of
small one-to-many groups with link-local scope. Such an
authentication mechanism should be considered along with the
router-to-Rendezvous Point authentication mechanism. The most
important issue is ensuring that only the "authorized neighbors"
get the keys for (S,G), so that rogue routers cannot participate
in the exchanges. Another issue is that some of the
communication may occur intra-domain, e.g. the link-local
messages in an enterprise, while others for the same (*,G) may
occur inter-domain, e.g. the router-to-Rendezvous Point messges
may be from one enterprise's router to another. One possible
solution proposes a region-wide "master" key server (possibly
replicated), and one "local" key server per speaking router.
There is no issue with propagating the messages outside the link,
because link-local messages, by definition, are not forwarded.
This solution is offered only as an example of how work may
progress; further discussion should occur in this work team.
Specification of a link-local protection mechanism for PIM-SM
occurred in RFC 4601 [RFC4601], and this work is being updated in
PIM-SM-LINKLOCAL [I-D.ietf-pim-sm-linklocal]. However, the KMP
part is completely unspecified, and will require work outside the
expertise of the PIM working group to accomplish, which is why
this roadmap is being created.
These protocols are deemed out-of-scope for this current iteration of
the work roadmap. Once all of the protocols listed above have had
their work completed, or are clearly within site of completion, then
the community will revisit the need and interest for working on
these:
o MANET
o FORCES
[need text from routing ADs on why these are out of scope]
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4.6. Priorites
Resources from both the routing area and the security area will be
applied to work on these problem spaces as quickly as possible.
Realizing that such resources are far from unlimited, a rank order
priority for addressing the work of incrementally securing these
groups of routing protocols is provided:
o Priority 1 - BGP / LDP / MSDP - almost done with Phase 1 on these,
via TCP-AO [I-D.ietf-tcpm-tcp-auth-opt] .
o Priority 2 - PIM-SM
o Priority 3 - OSPF / ISIS / RIP
o Priority 4 - BFD
o Priority 5 - RSVP and RSVP-TE
By far the most important group is the Priority 1 group as these are
the protocols used on the most public and exposed segments of the
networks, at the peering points between operators and between
operators and their customers. BFD, as a detection mechanism
underlying the Priority 1 protocols is therefore second.
5. Security Considerations
As mentioned in the Introduction , RFC4948 identifies additional
steps needed to achieve the overall goal of improving the security of
the core routing infrastructure. Those include validation of route
origin announcements, path validation, cleaning up the IRR databases
for accuracy, and operational security practicies that prevent
routers from being compromised devices. The KARP work is but one
step in a necessary system of security improvements.
The security of cryptographic-based systems depends on both the
strength of the cryptographic algorithms chosen and the strength of
the keys used with those algorithms. The security also depends on
the engineering of the protocol used by the system to ensure that
there are no non-cryptographic ways to bypass the security of the
overall system.
Care should also be taken to ensure that the selected key is
unpredictable, avoiding any keys known to be weak for the algorithm
in use. [RFC4086] contains helpful information on both key
generation techniques and cryptographic randomness.
In addition to using a stong key/PSK of appropriate length and
randomness, deployers of KARP protocols SHOULD use different keys
between different routing peers whenever operationally possible.
RFC3562 [RFC3562] provides some very sound guidance. It was meant
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specifically for the use of TCP MD5 for BGP, but it is more or less
applicable to Routing Protocol authentication work that would result
from KARP. It states three main points: (1) key lengths SHOULD be
between 12 and 24 bytes (this will vary depending on the MAC/KDF in
use), with larger keys having effectively zero additional
computational costs when compared to shorter keys, (2) key sharing
SHOULD be limited so that keys aren't shared among multiple BGP
peering arrangements, and (3) Keys SHOULD be changed at least every
90 days (this could be longer for stronger MAC algorithms, but it is
generally a wise idea).
This is especially true when the Routing Protocol takes a static
Traffic Key as opposed to a Traffic Key derived per-connection by a
KDF. The burdon for doing so is understandable much higher than for
using the same static Traffic Key across all peering routers. This
is why use of a KMP network-wide increases peer-wise security so
greatly, because now each set of peers can enjoys a unique Traffic
Key, and if an attacker sitting between two routers learns or guesses
the Traffic Key for that connection, she doesn't gain access to all
the other connections as well.
However, whenever using manual keys, it is best to design a system
where a given PSK will be used in a KDF, mixed with connection
specific material, in order to generate session unique -- and
therefore peer-wise -- Traffic Keys. Doing so has the following
advantages: the Traffic Keys used in the per-message MAC operation
are peer-wise unique, it provides inter-connection replay protection,
and, if the per-message MAC covers some connection counter, intra-
connection replay protection.
Note that in the composition of certain key derivation functions
(e.g. KDF_AES_128_CMAC, as used in TCP-AO [I-D.ao-crypto]), the
pseudorandom function (PRF) used in the KDF may require a key of a
certain fixed size as an input. For example, AES_128_CMAC requires a
128 bit (16 byte) key as the seed. However, for convenience to the
administrators/deployers, a specification may not want to force the
deployer to enter a PSK of exactly 16 bytes. Instead, a
specification may call for a sub-key routine that could handle a
variable length PSK, one that might be less than 16 bytes (see
[RFC4615], section 3, as an example). That sub-key routine would act
as a key extractor to derive a second key of exactly the required
length, and thus suitable as a seed to the PRF. This does NOT mean
that administrators are safe to use weak keys. Administrators are
encouraged to follow [RFC4086] as listed above. We simply attempted
to "put a fence around stupidity", in as much as possible.
A better option, from a security perspective, is to use some
representation of a device-specific assymetric key pair as the
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identity proof, as described in Section 3.4.2.
When it comes time for the KARP WG to design the re-usable model for
a KMP, The Guidelines for Cryptographic Key Management, RFC4107
[RFC4107] should be will be consulted.
[[QUESTION TO REVIEWERS: it may be worthwhile to pull the last few
paragraphs, along with some guidance along the same lines, into
section 4, in a new sub-section with a title something like "Security
tips for KARP design teams working on Routing Protocol reviews and
updates". Or maybe even into its own info document, "Security
Guidelines for KARP Design Teams".Thoughts?]]
The mechanisms that will be defined under this roadmap aim to improve
the security, better protect against more threats, and provider far
greater operational efficiencies than the state of things at the time
of this writing. However, none of these changes will improve
Internet security unless they are implemented and deployed. Other
influences must be brought to bare upon operators and organizations
to create incentives for deployment. Such incentives may take the
form of PCI-like industry compliance/certifications, well advertised
BCPs profiling the use of this roadmap's output, end-user demand or
insistance.
6. IANA Considerations
This document has no actions for IANA.
7. Acknowledgements
The outline for this draft was created from discussions and
agreements with Routing AD's Ross Callon and Dave Ward, Security AD's
Tim Polk and Pasi Eronen, and IAB members Danny McPherson and Gregory
Lebovitz.
Mat Ford and Bill Atwood provided reviews to -00.
Danny McPherson provided an extremely detailed and useful review of
-01.
8. Change History (RFC Editor: Delete Before Publishing)
[NOTE TO RFC EDITOR: this section for use during I-D stage only.
Please remove before publishing as RFC.]
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-00-00 original rough rough rough draft for review by routing and
security AD's
-00- original submission
o adds new category = multicast protocols in category section and
mentions mcast in group keying category description.
o add a lot of references where they did not exist before, or where
there were only place holders. Still more work needed on this.
o abstract filled in
o changed from standards track to informational (this was an
oversight in last draft).
o filled out threats section with detailed descriptions, and linked
to RPsec threats RFC
o made ascii art for the basic KMP framework
o added section on internal versus external peering and the
requirements decisions for them
o added security characterization section in sect 2, added sections
discussing internal vs external protocols, shared vs unique keys,
oob vs in-band keying
o incorporates all D Ward's feedback from his initial skim of the
document.
-01-
o Updated framework (Figure 1) diagram to include all listed and
described elements. Needs review and honing. Gregory Lebovitz
(GL).
o Added comment in protocols (Section 4.5) section that much of the
BGP/LDP Phase 1 work is already being done in tcp-ao and ao-
crypto. GL.
o Updated Scope making the 2 work phases more clear earlier in the
document. GL.
o Broke work items (Section 4.4) section into two Phases, 1 for
manual key update, and second for KMP work. GL.
o Re-org'd doc. Brought Threats (Section 2) section out into its
own top-level section. Did same with Categorization (Section 3)
section, leaving Roadmap section more focused. Moved ToDo list
and Change History to end of doc, after Acknowledgements. GL.
o added new sect 2.3 (Section 4.1) on main roadmap phases. Previous
section Common Framework (Section 4.3) moved to 2.4. Tim Polk
(TP).
o Added Section 2.3.1 Requirements for Phase 1 Routing Protocols'
Security Update (Section 4.2). This provides a nice starter set
of requirements for any work team. GL.
o Filled out text for Out vs In-band Key Mgmt (Section 3.4.3)
section, significantly. Changed the term from "in-band" to "in-
line".
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o Section Threats (Section 2) Clarified DoS threats in and out of
scope better. We are not preventing all DoS attacks. Just those
we can reasonably via authentication. TP.
o Sect In-band vs Out-of-Band (Section 3.4.3)clarified that In-band
does not mean in-band to Routing Protocol, but rather over IP
between the Routing Protocols, rather than pushed down by some
external management entity. TP.
o In roadmap (Section 3) section, added "it is also hoped that we
can create one kmp per category..." Also explained value of a
KMP. TP.
o Added "operators" to audience (Section 1.6) list. Matt Ford (MF).
o Described why BGP (and LDP) security is not deployed very often.
Added this Scope (Section 1.3) section, point 4. If mechanisms
aren't being deployed, why is that? What, if anything, could be
done to improve deployment? Tried to address these. Need
references (see To Do list below). MF.
o Added some text to security section to address this from MF: say
something here about the limitations of this approach, if any -
and refer back to the need for other pieces of the puzzle. May
need more work.
o Cleaned up text for multicast part of Message Type (Section 3.1)
section and Protocols (Section 4.5) section, clarifying PIM's two
message types, mcast and unicast, in both places. Bill Atwood
(BA).
o In section Protocols (Section 4.5), added references to 4601 and
PIM-SM-LINKLOCAL. BA.
o Editorial changes pointed out various folks.
-02-
o Re-submitted due to expiration. Text did not change. Substantive
update coming shortly.
o
o
- 03 -
o changed "BaseRP" to "Routing Protocol" throughout the doc - man
o filled out the Terminology section
o changed "KMART" to "KARP" in everything but the title, since the
-00 deadline had long since passed. Will change the title of the
doc to KARP as soon as the window re-opens.
o priorities in sect 4.6 changed. Added PIM-SM. Lowered OSPF and
BFD, based on feedback by a few people.
o many edits resulting from Danny McPherson's review.
o added "Brute Foce Attacks Against Password/Keys" to Threats
Section 2.1 section.
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o Significant updates to Security Considerations section
o Added a few references throughout to RFC3562
o 4.3 2nd to last P - added a comment to clarify that two parties
(or an org) must discuss ahead of time what they want their
connections' secruity properties to be. - dward
o added to 4.4 Phase 1 - New Section: Transition and Deployment
Considerations. ea wg must call out the operational transition
plan from old to new security. Best if don't bounce link. - dward
o added 3.3 (but not sure if this is right)- endpoint discovery
mechanisms? endpoint discovery mechanism (L2VPN, L3VPN, etc).
Discovery is much different security properties than passing
Routing updates. - dward
o More requirements: Added to 4.2: X - convergence SHOULD not be
affected by what we choose; adding security SHOULD not cause a
refresh of route updates or cause additional route updates to be
generated; adding auth should not be an attack vector itself.
AKA, the use of MD5 is so expensive that spoofing BGP packets w/
MD5 causes the control plane to be attacked because CPU went to
100% - dward
o updated stats on MD5 usage, and cited [ISR2008]. - mchpherson
9. Needs Work in Next Draft (RFC Editor: Delete Before Publishing)
[NOTE TO RFC EDITOR: this section for use during I-D stage only.
Please remove before publishing as RFC.]
List of stuff that still needs work
o RTG AD's or delegates: clean up the three definitions of route
message type categories. Need RTG Area folks input on this.
o More clarity on the work items for those defining and specifying
the framework elements and API's themselves.
o RTG AD's or delegates: text justifying RSVP and RSVP-TE and what
we think solving that problem may look like
o RTG AD's or delegates: more justification for why MANET and FORCES
are out of scope. Need ref for those RFCs.
o Danny McPherson: Get reference for BGP auth usage stats in Scope
(Section 1.3) section, item 4.
o
o security section: pull out security guidance to routing protocol
design teams stuff and place into its own section?
o
o
10. References
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10.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC4593] Barbir, A., Murphy, S., and Y. Yang, "Generic Threats to
Routing Protocols", RFC 4593, October 2006.
[RFC4948] Andersson, L., Davies, E., and L. Zhang, "Report from the
IAB workshop on Unwanted Traffic March 9-10, 2006",
RFC 4948, August 2007.
10.2. Informative References
[I-D.ao-crypto]
Lebovitz, G., "Cryptographic Algorithms, Use and
Implementation Requirements for TCP Authentication
Option", March 2009, <http://tools.ietf.org/html/
draft-lebovitz-ietf-tcpm-tcp-ao-crypto-00>.
[I-D.ietf-pim-sm-linklocal]
Atwood, W., Islam, S., and M. Siami, "Authentication and
Confidentiality in PIM-SM Link-local Messages",
draft-ietf-pim-sm-linklocal-09 (work in progress),
October 2009.
[I-D.ietf-tcpm-tcp-auth-opt]
Touch, J., Mankin, A., and R. Bonica, "The TCP
Authentication Option", draft-ietf-tcpm-tcp-auth-opt-08
(work in progress), October 2009.
[ISR2008] McPherson, D. and C. Labovitz, "Worldwide Infrastructure
Security Report", October 2008,
<http://www.arbornetworks.com/dmdocuments/ISR2008_US.pdf>.
[RFC1195] Callon, R., "Use of OSI IS-IS for routing in TCP/IP and
dual environments", RFC 1195, December 1990.
[RFC2328] Moy, J., "OSPF Version 2", STD 54, RFC 2328, April 1998.
[RFC2453] Malkin, G., "RIP Version 2", STD 56, RFC 2453,
November 1998.
[RFC3562] Leech, M., "Key Management Considerations for the TCP MD5
Signature Option", RFC 3562, July 2003.
[RFC3618] Fenner, B. and D. Meyer, "Multicast Source Discovery
Protocol (MSDP)", RFC 3618, October 2003.
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[RFC3973] Adams, A., Nicholas, J., and W. Siadak, "Protocol
Independent Multicast - Dense Mode (PIM-DM): Protocol
Specification (Revised)", RFC 3973, January 2005.
[RFC4086] Eastlake, D., Schiller, J., and S. Crocker, "Randomness
Requirements for Security", BCP 106, RFC 4086, June 2005.
[RFC4107] Bellovin, S. and R. Housley, "Guidelines for Cryptographic
Key Management", BCP 107, RFC 4107, June 2005.
[RFC4271] Rekhter, Y., Li, T., and S. Hares, "A Border Gateway
Protocol 4 (BGP-4)", RFC 4271, January 2006.
[RFC4301] Kent, S. and K. Seo, "Security Architecture for the
Internet Protocol", RFC 4301, December 2005.
[RFC4303] Kent, S., "IP Encapsulating Security Payload (ESP)",
RFC 4303, December 2005.
[RFC4306] Kaufman, C., "Internet Key Exchange (IKEv2) Protocol",
RFC 4306, December 2005.
[RFC4601] Fenner, B., Handley, M., Holbrook, H., and I. Kouvelas,
"Protocol Independent Multicast - Sparse Mode (PIM-SM):
Protocol Specification (Revised)", RFC 4601, August 2006.
[RFC4615] Song, J., Poovendran, R., Lee, J., and T. Iwata, "The
Advanced Encryption Standard-Cipher-based Message
Authentication Code-Pseudo-Random Function-128 (AES-CMAC-
PRF-128) Algorithm for the Internet Key Exchange Protocol
(IKE)", RFC 4615, August 2006.
[RFC4949] Shirey, R., "Internet Security Glossary, Version 2",
RFC 4949, August 2007.
[RFC5036] Andersson, L., Minei, I., and B. Thomas, "LDP
Specification", RFC 5036, October 2007.
[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 5226,
May 2008.
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Authors' Addresses
Gregory Lebovitz
Juniper Networks, Inc.
1194 North Mathilda Ave.
Sunnyvale, CA 94089-1206
US
Phone:
Email: gregory.ietf@gmail.com
Phone:
Email:
Lebovitz & Expires May 9, 2010 [Page 43]
discovery process. These messages are normally
exchanged prior to any adjacency being formed, and
before any updates are sent. For example, end-point
discovery mechanisms are common in L2VPN and L3VPN
solutions.
[QUESTION TO REVIEWERS: is this really just what's described in 3.1
as "Client-Server" and/or "One-to-One"? Is there really such a
different in discovery protocols that they need their own category to
figure out how to authenticate them? Can someone provide a few
examples?
3.4. Security Characterization Vectors
A few more considerations must be made about the protocol and its use
when initially categorizing the protocol and scoping the
authentication work.
3.4.1. Internal vs. External Operation
The designers must consider whether the protocol is an internal
routing protocol or an external one, i.e. Does it primarily run
between peers within a single domain of control or between two
different domains of control? Some protocols may be used in both
cases, internally and externally, and as such various modes of
authentication operation may be required for the same protocol.
While it is preferred that all routing exchanges run with the utmost
security mechanisms enabled in all deployments, this exhortation is
greater for those protocols running on inter-domain point-to-point
links, and greatest for those on shared access link layers with
several different domains interchanging together, because the volume
of attackers are greater from the outside. Note however that the
consequences of internal attacks maybe no less severe -- in fact they
may be quite a bit more severe -- than an external attack. An
example of this internal versus external consideration is BGP which
has both EBGP and IBGP modes. Another example is a multicast
protocol where the neighbors are sometimes within a domain of control
and sometimes at an inter-domain exchange point. In the case of
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PIM-SM running on an internal multi-access link, It would be
acceptable to give up some security to get some convenience by using
a group key between the peers on the link. On the other hand, in the
case of PIM-SM running over a multi-access link at a public exchange
point, operators may favor security over convenience by using unique
pair-wise keys for every peer. Designers must consider both modes of
operation and ensure the authentication mechanisms fit both.
Operators are encouraged to run cryptographic authentication on all
their adjacencies, but to work from the outside in, i.e. The EBGP
links are a higher priority than the IBGP links because they are
externally facing, and, as a result, more likely to be targeted in an
attack.
3.4.2. Unique versus Shared Keys
This section discusses security considerations regarding when it is
appropriate to use the same authentication key inputs for multiple
peers and when it is not. This is largely a debate of convenience
versus security. It is often the case that the best secured
mechanism is also the least convenient mechanism. For example, an
air gap between a host and the network absolutely prevents remote
attacks on the host, but having to copy and carry files using the
"sneaker net" is quite inconvenient and unscalable.
Operators have erred on the side of convenience when it comes to
securing routing protocols with cryptographic authentication. Many
do not use it at all. Some use it only on external links, but not on
internal links. Those that do use it often use the same key for all
peers across their entire network. It is common to see the same key
in use for years, and that being the same key that was entered when
authentication was originally configured, or the routing gear
deployed.
The goal for designers is to create authentication mechanisms that
are easy for the operators to deploy and manage, and still use unique
keys between peers (or small groups on multi-access links), and
within between sessions. Operators have the impression that they
NEED one key shared across the network, when in fact they do not.
What they need is the relative convenience they experience from
deploying cryptographic authentication with one (or few) key,
compared to the inconvenience they would experience if they deployed
the same authentication mechanism using unique pair-wise keys. An
example is BGP Route Reflectors. Here operators often use the same
authentication key between each client and the route reflector. The
roadmaps defined from this guidance document will allow for unique
keys to be used between each client and the peer, without sacrificing
much convenience. Designers should strive to deliver peer-wise
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unique keying mechanisms with similar ease-of-deployment properties
as today's one-key method.
Operators must understand the consequences of using the same keys
across many peers. Unique keys are more secure than shared keys
because they reduce both the attack target size and the attack
consequence size. In this context, the attack target size represents
the number of unique routing exchanges across a network that an
attacker may be able to observe in order to gain security association
credentials, i.e. crack the keys. If a shared key is used across the
entire internal domain of control, then the attack target size is
very large. The larger the attack target, the easier it is for the
attacker to gain access to analysis data, and greater the volume of
analysis data he can access in a given time frame, both of which make
his job easier. Using the same key across the network makes the
attack vulnerability surface more penetrable than unique keys.
Consider also the attack consequence size, the amount of routing
adjacencies that can be negatively affected once a breach has
occurred, i.e. once the keys have been acquired by the attacker.
Again, if a shared key is used across the internal domain, then the
consequence size is the whole network. Ideally, unique key pairs
would be used for each adjacency.
In some cases designers may need to use shared keys in order to solve
the given problem space. For example, a multicast packet is sent
once but then observed and consumed by several routing neighbors. If
unique keys were used per neighbor, the benefit of multicast would be
erased because the casting peer would have to create a different
announcement packet/stream for each listening peer. Though this may
be desired and acceptable in some small amount of use cases, it is
not the norm. Shared group keys are an acceptable solution here, and
much work has been done already in this area (see MSEC working
group).
3.4.3. Out-of-Band vs. In-line Key Management
This section discusses the security and use case considerations for
keys placed on devices through out-of-band configurations versus
through one routing peer-to-peer key management protocol exchanges.
Note, when we say here "Peer-to-Peer KMP" we do not mean in-band to
the Routing Protocol. Instead, we mean that the exchange occurs in-
line, over IP, between the two routing peers directly. In in-line
KMP the peers themselves handle the key and security association
negotiation between themselves directly, whereas in an out-of-band
system the keys are placed onto the device through some other
configuration or management method or interface.
An example of an out-of-band mechanism could be an administrator who
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makes a remote management connection (e.g. using SSH) to a router and
manually enters the keying information -- like the algorithm, the
key(s), the lifetimes, etc. Another example could be an OSS system
which inputs the same information via a script over an SSH
connection, or by pushing configuration through some other management
connection, standard (Netconf-based) or proprietary.
The drawbacks of an out-of-band mechanism include: lack of scale-
ability, complexity and speed of changing if a breach is suspected.
For example, if an employee who had access to keys was was
terminated, or if a machine holding those keys was belived
compromised, then the system would be considered insecure and
vulnerable until new keys were defined by a human. Those keys then
need to be placed into the OSS system, manually, and the OSS system
then needs to push the change -- often during a very limited change
window -- into the relevant devices. If there are multiple
organizations involved in these connections, this process is greatly
complicated.
The benefits of out-of-band mechanism is that once the new keys/
parameters are set in OSS system they can be pushed automatically to
all devices within the OSS's domain of control. Operators have
mechanisms in place for this already. In small environments with few
routers, a manual system is not difficult to employ.
We further define an in-line key exchange as using cryptographicly
protected identity verification, session key negotiation, and
security association parameter negotiation between the two routing
peers. The KMP between the two peers may also include the
negotiation of parameters, like algorithms, cryptographic inputs
(e.g. initialization vectors), key life-times, etc.
The benefits an in-line KMP are several. An in-line KMP results in
key(s) that are privately generated, and not recorded permanently
anywhere. Since the traffic keys used in a particular connection are
not a fixed part of a device configuration no steal-able data exists
anywhere else in the operator's systems which can be stolen, e.g. in
the case of a terminated or turned employee. If a server or other
data store is stolen or compromised, the thieves gain no access to
current traffic keys. They may gain access to key derivation
material, like a PSK, but not current traffic keys in use. In this
example, these PSKs can be updated into the device configurations
(either manually or through an OSS) without bouncing or impacting the
existing session at all. In the case of using raw assymetric keys or
certificates, instead of PSKs, the data theft would likely not even
result in any compromise, as the key pairs would have been generated
on the routers, and never leave those routers. In such a case no
changes are needed on the routers; the connections will continue to
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be secure, uncompromised. Additionally, with a KMP regular re-keys
operations occur without any operator involvement or oversight. This
keeps keys fresh.
The drawbacks to using a KMP are few. First, a KMP requires more
cryptographic processing for the router at the very beginning of a
connection. This will add some minor start-up time to connection
establishment versus a purely manual key approach. Once a connection
with traffic keys have been established via a KMP, the performance is
the same in the KMP and the out-of-band case. KMPs also add another
layer of protocol and configuration complexity which can fail or be
misconfigured. This was more of an issue when these KMPs were first
deployed, but less so as these implementaitons and operational
experience with them has matured.
The desired end goal is in-line KMPs.
4. The Roadmap
4.1. Work Phases on any Particular Protocol
The desired endstate for the KARP work contains several items.
First, the people desiring to deploy securely authenticated and
integrity validated packets between routing peers have the tools
specified, implemented and shipping in order to deploy. These tools
should be fairly simple to implement, and not more complex than the
security mechanisms to which the operators are already accustomed.
(Examples of security mechanisms to which router operators are
accustomed include: the use of assymetric keys for authentication in
SSH for router configuration, the use of pre-shared keys (PSKs) in
TCP MD5 for BGP protection, the use of self-signed certificates for
HTTPS access to device Web-based user interfaces, the use of strongly
constructed passwords and/or identity tokens for user identification
when logging into routers and management systems.) While the tools
that we intend to specify may not be able to stop a deployment from
using "foobar" as an input key for every device across their entire
routing domain, we intend to make a solid, modern security system
that is not too much more difficult than that. In other words,
simplicity and deployability are keys to success. The Routing
Protocols will specify modern cryptographic algorithms and security
mechanisms. Routing peers will be able to employ unique, pair-wise
keys per peering instance, with reasonable key lifetimes, and
updating those keys on a somewhat regular basis will be operationally
easy, causing no service interruption.
Achieving the above described end-state using manual keys may only be
pragmatic in very small deployments. In larger deployments, this end
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state will be much more operationally difficult to reach with only
manual keys. Thus, there will be a need for key life cycle
management, in the form of a key management protocol, or KMP. We
expect that the two forms, manual key usage and KMP usage, will co-
exist in the real world. For example, a provider's edge router at a
public exchange peering point will want to use a KMP for ensuring
unique and fresh keys with external peers, while a manual key may be
used between a provider's access edge router and each of the same
provider's customer premise routers with which it peers.
In accordance with the desired end state just described, we define
two main work phases for each Routing Protocol:
1. Enhance the Routing Protocol's current authentication mechanism.
This work involves enhancing a Routing Protocol's current
security mechanisms in order to achieve a consistent, modern
level of security functionality within its existing keying
framework. It is understood and accepted that the existing
keying frameworks are largely based on manual keys. Since many
operators have already built operational support systems (OSS)
around these manual key implementations, there is some automation
available for an operator to leverage in that way, if the
underlying mechanisms are themselves secure. In this phase, we
explicitly exclude embedding or creating a KMP. A list of the
requirements for Phase 1 work are below in the section
"Requirements for Phase 1 Routing Protocols' Security Updates
(Section 4.2).
2. Develop an automated keying framework. The second phase will
focus on the development of an automated keying framework to
faciliate unique pair-wise (or perhaps group-wise, where
applicable) keys per peering instance. This involves the use of
a KMP. A KMP is helpful because it negotiates unique, pair wise,
random keys without administrator involvement. It also
negotiates several of the SA parameters required for the secure
connection, including key life times. It keeps track of those
lifetimes using counters, and negotiates new keys and parameters
before they expire, again, without administrator interaction.
Additionally, in the event of a breach, changing the KMP key will
immediately cause a rekey to occur for the Traffic Key, and those
new Traffic Keys will be installed and used in the current
connection. In summary, a KMP provides a protected channel
between the peers through which they can negotiate and pass
important data required to exchange proof of key identifiers,
derive Traffic Keys, determine re-keying, synchronize their
keying state, signal various keying events, notify with error
messages, etc. To address brute force attacks [RFC3562]
recommends a key management practice to minimize the possibility
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of successful attack-- frequent key rotation, limited key
sharing, key length restrictions, etc. Advances in computational
power due to Moore's law are making that management burden
untenable-- keys must be of a size and composition that makes
configuration and maintance difficult or keys must be rotated
with an unreasonable frequency. A KMP will help immensely with
this growing problem.
The framework for any one Routing Protocol will fall under, and
be able to leverage, the generic framework described below in
section Section 4.3.
4.2. Requirements for Phase 1 Routing Protocols' Security Update
Here is a proposed list of requirements that SHOULD be addressed by
Phase 1 (according to "1." above) security updates to Routing
Protocols [to be reviewed after -01 is released]:
1. Clear definitions of which elements of the transmission (frame,
packet, segment, etc.) are protected by the authentication
mechanism
2. Strong algorithms, and defined and accepted by the security
community, MUST be specified. The option should use algorithms
considered accepted by the security community, which are
considered appropriately safe. The use of non-standard or
unpublished algorithms SHOULD BE avoided.
3. Algorithm agility for the cryptograhpic algorithms used in the
authentication MUST be specified, i.e. more than one algorithm
MUST be specified and it MUST be clear how new algorithms MAY be
specified and used within the protocol. This requirement exists
in case one algorithm gets broken suddenly. Research to
identify weakness in algorithms is constant. Breaking a cipher
isn't a matter of if, but when it will occur. t's highly
unlikely that two different algorithms will be broken
simultaneously. So, if two are supported, and one gets broken,
we can use the other until we get a new one in place. Having
the ability within the protocol specification to support such an
event, having algorithm agility, is essential. Mandating two
algorithms provides both a redundancy, and a mechanism for
enacting that redundancy when needed.
4. Secure use of simple PSKs, offering both operational convenience
as well as building something of a fence around stupidity, MUST
be specified.
5. Inter-connection replay protection. Packets captured from one
connection MUST NOT be able to be re-sent and accepted during a
later connection.
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6. Intra-connection replay protection. Packets captured during a
connection MUST NOT be able to be re-sent and accepted during
that same connection, to deal with long-lived connections.
7. A change of security parameters REQUIRES, and even forces, a
change of session traffic keys
8. Intra-connection re-keying which occurs without a break or
interruption to the current peering session, and, if possible,
without data loss, MUST be specified.
9. Efficient re-keying SHOULD be provided. The specificaion SHOULD
support rekeying during a connection without the need to expend
undue computational resources. In particular, the specification
SHOULD avoid the need to try/compute multiple keys on a given
packet.
10. Prevent DoS attacks as those described as in-scope in the
threats section Section 2.1 above.
11. Default mechanisms and algorithms specified and defined as
REQUIRED for all implementations
12. Manual keying MUST be supported.
13. Convergence times of the Routing Protocols SHOULD NOT be
materially affected. Materially here is defined as anything
greater than a 5% convergence time increase. Note that
convergence is different than boot time. Also note that
convergence time has a lot to do with the speed of processors
used on individual routing peers, and this increases by Moore's
law over time. Therefore, this requirement should be considered
only in terms of total number of messages that must be
exchanged, and less for the computational intensity of
processing any one message.
14. The changes or addition of security mechanisms SHOULD NOT cause
a refresh of route updates or cause additional route updates to
be generated
15. Architecture of the specification MUST consider and allow for
future use of a KMP.
4.3. Common Framework
Each of the categories of routing protocols above will require unique
designs for authenticating and integrity checking their protocols.
However, a single underlying framework for delivering automatic
keying to those solutions will be pursued. Providing such a single
framework will significantly reduce the complexity of each step of
the overall roadmap. For example, if each Routing Protocol needed to
define it's own key management protocol this would balloon the total
amount of different sockets that are needed to be opened and
processes that are needed to be simultaneously running on an
implementation. It would also significantly increase the run-time
complexity and memory requirements of such systems running multiple
Routing Protocols, causing perhaps slower performance of such
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systems. However, if we can land on a very small set (perhaps one or
two) of automatic key management protocols, KMPs, that the various
Routing Protocols can use, then we can reduce this implementation and
run-time complexity. We can also decrease the total amount of time
implementers need to deliver the KMPs for the Routing Protocols that
will provide better threat protection.
The components for the framework are listed here, and described
below:
o Routing Protocol security mechanism
o KMP
o KeyStore
o Traffic Key
o RoutingProtocol-to-KMP API
o RoutingProtocol-to-KeyStore API
o KMP-to-KeyStore API
o Common Routing Protocol mechanisms
o Identifiers
o Proof of identity
o Profiles
The framework is modularized for how keys and security association
(SA) parameters generally get passed from a KMP to a transport
protocol. It contains three main blocks and APIs.
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+------------+ +--------------------+
| | | | Check +-----------+
| Identifier +-->| +---------->| |
| | | KMP Function | | Identity |
+----------- + | |<----------+ Proof |
| | Approve | |
+-+--------------+---+ +-----------+
| |
KMP-to-KeyStore | |
API | |
\|/ |
+-------+-------+ |
| | | KMP-to-RoutingProtocol
| | | API
| KeyStore | |
| | |
+-------+-------+ |
| |
| |
KeyStore-to- | |
RoutingProtocol API | |
| \|/
+--------------------------+-------------+
| | |
| \|/ Common RtgProto |
| +-------+-------+ Authentication |
| | | Mechanisms |
+---| Traffic |-----+--------------+
| | Key(s) | |
| | | |
| +---------------+ Specific |
| RoutingProtocol |
| Authentication |
| Security |
| Mechanism |
+----------------------------------------+
Figure 1: Automatic Key Management Framework
Each element of the framework is described here:
o Routing Protocol - Routing protocol security mechanism - In each
case, the Routing Protocol will contain a mechanism for using
session keys in their security option. When the Routing
Protocol uses a transport substrate, e.g. the way BGP, LDP
and MSDP use TCP, then this applies to the security mechanism
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the includes that substrate.
o KeyStore - Each implementation will also contain a protocol
independent mechanism for storing keys, called KeyStore. The
KeyStore will have multiple different logical containers, one
container for each session key that any given Routing
Protocol will need. Keys stored here may be a Peer Key or a
Traffic Key. There may also be associated parameters as
required by the SA for any given Routing Protocol.
o Peer Key A key used between peers from which a traffic key is
derived. An example is a PSK.
o Traffic Key The actual key used on each packet of a message.
This key may be derived from the key existing in the
KeyStore. This will depend on whether the key in KeyStore
was a manual PSK for the peers, or whether a connection-aware
KMP created the key. Further, it will be connection
specific, so as to provide inter- and intra-connection replay
protection.
o RoutingProtocol-KeyStore API - There will be an API for Routing
Protocol to retrieve (or receive; it could be a push or a
pull) the keys from the KeyStore. This will enable
implementers to reuse the same API calls for all their
Routing Protocols. The API will necessarily include facility
to retrieve other SA parameters required for the construction
of the Routing Protocol's packets, like key IDs or key
lifetimes, etc.
o KMP - There will be an automated key management protocol, KMP.
This KMP will run between the peers. The KMP serves as a
protected channel between the peers, through which they can
negotiate and pass important data required to exchange proof
of key identifiers, derive session keys, determine re-keying,
synchronize their keying state, signal various keying events,
notify with error messages, etc. As an analogy, in the IPsec
protocol (RFC4301 [RFC4301], RFC4303 [RFC4303] and RFC4306
[RFC4306]) IKEv2 is the KMP that runs between the two peers,
while AH and ESP are two different base protocols that take
session keys from IKEv2 and use them in their transmissions.
In the analogy, the Routing Protocol, say BGP and LDP, are
analogous to ESP and AH, while the KMP is analogous to IKEv2
itself.
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o RoutingProtocol-KMP API - There will be an API for the Routing
Protocol to request a session key of the KMP, and be notified
when the keys are available for it. The API will also
contain a mechanism for the KMP to notify the Routing
Protocol that there are new keys that it must now use, even
if it didn't request those keys. The API will also include a
mechanism for the KMP to receive requests for session keys
and other parameters from the routing protocol. The KMP will
also be aware of the various Routing Protocols and each of
their unique parameters that need to be negotiated and
returned.
o KMP-KeyStore API - There will be an API for the KMP to place
keys and parameters into the KeyStore after their negotiation
and derivation with the other peer. This will enable the
implementers to reuse the same calls for multiple KMPs that
may be needed to address the various categories of Routing
Protocols as described in the section definingcategories
(Section 3).
[after writing this all up, I'm not sure we really need the key_store
in the middle. As long as we standardize fully all the calls needed
from any Routing Protocol to any KMP, then there can be a generic
hand-down function from the KMP to the Routing Protocol when the key
and parameters are ready. Let's sleep on it.]
[will need state machines and function calls for these APIs, as one
of the work items. In essence, there is a need for a core team to
develop the APIs out completely in order for the Routing Protocol
teams to use them. Need to get this team going asap.]
o Identifiers - A KMP is fed by identities. The identities are
text strings used by the peers to indicate to each other that
each are known to the other, and authorized to establish
connections. Those identities must be represented in some
standard string format, e.g. an IP address -- either v4 or
v6, an FQDN, an RFC 822 email address, a Common Name [RFC
PKI], etc. Note that even though routers do not normally
have email addresses, one could use an RFC 822 email address
string as a formatted identifier for a router. They would do
so simply by putting the router's reference number or name-
code as the "NAME" part of the address, left of the "@"
symbol. They would then place some locational context in the
"DOMAIN" part of the string, right of the "@" symbol. An
example would be "rtr0210@sf.ca.us.company.com". This
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document does not suggest this string value at all. Instead,
the concept is used only to clarify that the type of string
employed does not matter. It also does not matter what
specific text you chose to place in that string type. It
only matters that the type of string -- and it's format --
must be agreed upon by the two endpoints. Further, the
string can be used as an identifier in this context, even if
the string is not actually provisioned in it's source domain.
For example, the email address "rtr0210@sf.ca.us.company.com"
may not actually exist as an email address in that domain,
but that string of characters may still be used as an
identifier type(s) in the routing protocol security context.
What is important is that the community decide on a small but
flexible set of Identifiers they will all support, and that
they decide on the exact format of those string. The formats
that will be used must be standardized and must be sensible
for the routing infrastructure.
o Identity Proof - Once the form of identity is decided, then
there must be a cryptographic proof of that identity, that
the peer really is who they assert themselves to be. Proof
of identity can be arranged between the peers in a few ways,
for example pre-shared keys, raw assymetric keys, or a more
user-friendly representation of assymetric keys, like a
certificate. Certificates can be used in a way requiring no
additional supporting systems -- e.g. public keys for each
peer can be maintained locally for verification upon contact.
Certificate management can be made more simple and scalable
with the use minor additional supporting systems, as is the
case with self-signed certificates and a flat file list of
"approved thumbprints". Self-signed certificates will have
somewhat lower security properties than Certificate Authority
signed certificates [RFC Certs]. The use of these different
identity proofs vary in ease of deployment, ease of ongoing
management, startup effort, ongoing effort and management,
security strength, and consequences from loss of secrets from
one part of the system to the rest of the system. For
example, they differ in resistance to a security breach, and
the effort required to remediate the whole system in the
event of such a breach. The point here is that there are
options, many of which are quite simple to employ and deploy.
o Profiles - Once the KMP, Identifiers and Proofs mechanisms are
converged upon, they must be clearly profiled for each
Routing Protocol, so that implementors and deployers alike
understand the different pieces of the solution, and can have
similar configurations and interoperability across multiple
vendors' devices, so as to reduce management difficulty. The
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profiles SHOULD also provide guidance on when to use which
various combinations of options. This will, again, simplify
use and interoperability.
In addition to other business, administrative, and operational terms
they must already exchange prior to forming first adjacencies, it is
assumed that two parties deploying message authentication on their
routing protocol will also need to decide upon acceptable security
parameters for the connection. This will include the form and
content of the identity each use to represent the other. It will
also include the type of keys to be used, e.g. PSK, raw assymetric
keys, certificate. And it will include the acceptable cryptographic
algorithms, or algorithm suite. This agreement is necessary in order
for each to properly configure the connection on their respective
devices. The manner in which they agree upon and exchange this
policy information is normally via phone call or written exchange,
and is outside the scope of the KARP effort, but assumed to have
occured. We take as a given that each party knows the identity types
and values, key types and values, and acceptable cryptographic
algorithms for both their own device and the peer that form the
security policy for configuration on their device.
Common Mechanisms - In as much as they exist, the framework will
capture mechanisms that can be used commonly not only within a
particular category of Routing Protocol and Routing Protocol to KMP,
but also between Routing Protocol categories. Again, the goal here
is simplifying the implementations and runtime code and resource
requirements. There is also a goal here of favoring well vetted,
reviewed, operationally proven security mechanisms over newly brewed
mechanisms that are less well tried in the wild.
4.4. Work Items Per Routing Protocol
Each Routing Protocol will have a team (the [Routing_Protocol]-KARP
team) working on incrementally improving their Routing Protocol's
security, These teams will have the following main work items:
PHASE 1:
Characterize the RP
Assess the Routing Protocol to see what authentication mechanisms
it has today. Does it needs significant improvement to its
existing mechanisms or not? This will include determining if
modern, strong security algorithms and parameters are present.
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Define Optimal State
List the requirements for the Routing Protocol's session key usage
and format to contain to modern, strong security algorithms and
mechanisms, per the Requirements (Section 4.2) section above. The
goal here is to determine what is needed for they Routing Protocol
alone to be used securely with at least manual keys.
Gap Analysis
Enumerate the requirements for this protocol to move from its
current security state, the first bullet, to its optimal state, as
listed just above.
Transition and Deployment Considerations Document the operational
transition plan for moving from the old to the new security
mechanism. Will adjacencies need to bounce? What new elements/
servers/services in the infrastructure will be required? What is
an example work flow that an operator will take? The best
possible case is if the adjacency does not break, but this may not
always be possible.
Define, Assign, Design
Create a deliverables list of the design and specification work,
with milestones. Define owners. Release a document(s)
PHASE 2:
KMP Analysis
Review requirements for KMPs [RFC????]. Identify any nuances for
this particular protocol's needs and its use cases for KMP. List
the requirements that this Routing Protocol has for being able to
be use in conjunctions with a KMP. Define the optimal state.
Gap Analysis
Enumerate the requirements for this protocol to move from its
current security state to its optimal state.
Define, Assign, Design
Create a deliverabels list of the design and specification work,
with miletsones. Define owners. Do the design and document work
for a KMP to be able to generate the Routing Protocol's session
keys for the packets on the wire. These will be the arguments
passed in the API to the KMP in order to bootstrap the session
keys to the Routing Protocol.
There will also be a team formed to work on the base framework
mechanisms for each of the main categories, i.e. the blocks and API's
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represented in figure 1 (Figure 1).
4.5. Protocols in Categories
This section groups the Routing Protocols into like categories,
according to attributes set forth in Categories Section (Section 3).
Each group will have a design team tasked with improving the security
of the Routing Protocol mechanisms and defining the KMP requirements
for their group, then rolling both into a roadmap document upon which
they will execute.
BGP, LDP and MSDP
The Routing Protocol's that fall into the category of the one-to-
one peering messages, and will use peer keying protocols, AND are
all transmitted over TCP include BGP RFC 4271 [RFC4271], LDP
[RFC5036] and MSDP [RFC3618]. A team will work on one mechanism
to cover these three protocols. Much of the work on the Routing
Protocol update for its existing authentication mechanism is
already occuring in the TCPM Working Group, on the TCP-AO
[I-D.ietf-tcpm-tcp-auth-opt] document, as well as its
cryptography-helper document, TCP-AO-CRYPTO [I-D.ao-crypto]. The
exception is the mode where LDP is used directly on the LAN
[RFC????]. The work for this may go into the Group keying
category (w/ OSPF) mentioned below.
OSPF, ISIS, and RIP
The Routing Protocols that fall into the category Group keying
with one-to-many peering messages includes OSPF [RFC2328], ISIS
[RFC1195] and RIP [RFC2453]. Not surprisingly, all these routing
protocols have two other things in common. First, they are run
on a combination of the OSI datalink layer 2, and the OSI network
layer 3. By this we mean that they have a component of how the
routing protocol works which is specified in Layer 2 as well as
in Layer 3. Second, they are all internal gateway protocols, or
IGPs. The keying mechanisms and use will be much more
complicated to define for these than for a one-to-one messaging
protocol.
BFD
Because it is less of a routing protocol, per se, and more of a
peer aliveness detection mechanism, Bidirectional Forwarding
Detection (BFD) [RFC????] will have its own team.
RSVP [RFC????], RSVP-TE [RFC????], and PCE
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These three protocols will be handled together. [what more
characterisation should we give here? Routing AD's, provide text
pls?]
PIM-SM and PIM-DM
Finally, the multicast protocols of PIM-SM [RFC4601] and PIM-DM
[RFC3973] will be handled together. PIM-SM multicasts routing
information (Hello, Join/Prune, Assert) on a link-local basis,
using a defined multicast address. In addition, it specifies
unicast communication for exchange of information (Register,
Register-Stop) between the router closest to a group sender and
the "rendezvous point" (RP). The RP is typically not "on-link"
for a particular router. While much work has been done on
multicast security for application-layer groups, little has been
done to address the problem of managing hundreds or thousands of
small one-to-many groups with link-local scope. Such an
authentication mechanism should be considered along with the
router-to-Rendezvous Point authentication mechanism. The most
important issue is ensuring that only the "authorized neighbors"
get the keys for (S,G), so that rogue routers cannot participate
in the exchanges. Another issue is that some of the
communication may occur intra-domain, e.g. the link-local
messages in an enterprise, while others for the same (*,G) may
occur inter-domain, e.g. the router-to-Rendezvous Point messges
may be from one enterprise's router to another. One possible
solution proposes a region-wide "master" key server (possibly
replicated), and one "local" key server per speaking router.
There is no issue with propagating the messages outside the link,
because link-local messages, by definition, are not forwarded.
This solution is offered only as an example of how work may
progress; further discussion should occur in this work team.
Specification of a link-local protection mechanism for PIM-SM
occurred in RFC 4601 [RFC4601], and this work is being updated in
PIM-SM-LINKLOCAL [I-D.ietf-pim-sm-linklocal]. However, the KMP
part is completely unspecified, and will require work outside the
expertise of the PIM working group to accomplish, which is why
this roadmap is being created.
These protocols are deemed out-of-scope for this current iteration of
the work roadmap. Once all of the protocols listed above have had
their work completed, or are clearly within site of completion, then
the community will revisit the need and interest for working on
these:
o MANET
o FORCES
[need text from routing ADs on why these are out of scope]
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4.6. Priorites
Resources from both the routing area and the security area will be
applied to work on these problem spaces as quickly as possible.
Realizing that such resources are far from unlimited, a rank order
priority for addressing the work of incrementally securing these
groups of routing protocols is provided:
o Priority 1 - BGP / LDP / MSDP - almost done with Phase 1 on these,
via TCP-AO [I-D.ietf-tcpm-tcp-auth-opt] .
o Priority 2 - PIM-SM
o Priority 3 - OSPF / ISIS / RIP
o Priority 4 - BFD
o Priority 5 - RSVP and RSVP-TE
By far the most important group is the Priority 1 group as these are
the protocols used on the most public and exposed segments of the
networks, at the peering points between operators and between
operators and their customers. BFD, as a detection mechanism
underlying the Priority 1 protocols is therefore second.
5. Security Considerations
As mentioned in the Introduction , RFC4948 identifies additional
steps needed to achieve the overall goal of improving the security of
the core routing infrastructure. Those include validation of route
origin announcements, path validation, cleaning up the IRR databases
for accuracy, and operational security practicies that prevent
routers from being compromised devices. The KARP work is but one
step in a necessary system of security improvements.
The security of cryptographic-based systems depends on both the
strength of the cryptographic algorithms chosen and the strength of
the keys used with those algorithms. The security also depends on
the engineering of the protocol used by the system to ensure that
there are no non-cryptographic ways to bypass the security of the
overall system.
Care should also be taken to ensure that the selected key is
unpredictable, avoiding any keys known to be weak for the algorithm
in use. [RFC4086] contains helpful information on both key
generation techniques and cryptographic randomness.
In addition to using a stong key/PSK of appropriate length and
randomness, deployers of KARP protocols SHOULD use different keys
between different routing peers whenever operationally possible.
RFC3562 [RFC3562] provides some very sound guidance. It was meant
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specifically for the use of TCP MD5 for BGP, but it is more or less
applicable to Routing Protocol authentication work that would result
from KARP. It states three main points: (1) key lengths SHOULD be
between 12 and 24 bytes (this will vary depending on the MAC/KDF in
use), with larger keys having effectively zero additional
computational costs when compared to shorter keys, (2) key sharing
SHOULD be limited so that keys aren't shared among multiple BGP
peering arrangements, and (3) Keys SHOULD be changed at least every
90 days (this could be longer for stronger MAC algorithms, but it is
generally a wise idea).
This is especially true when the Routing Protocol takes a static
Traffic Key as opposed to a Traffic Key derived per-connection by a
KDF. The burdon for doing so is understandable much higher than for
using the same static Traffic Key across all peering routers. This
is why use of a KMP network-wide increases peer-wise security so
greatly, because now each set of peers can enjoys a unique Traffic
Key, and if an attacker sitting between two routers learns or guesses
the Traffic Key for that connection, she doesn't gain access to all
the other connections as well.
However, whenever using manual keys, it is best to design a system
where a given PSK will be used in a KDF, mixed with connection
specific material, in order to generate session unique -- and
therefore peer-wise -- Traffic Keys. Doing so has the following
advantages: the Traffic Keys used in the per-message MAC operation
are peer-wise unique, it provides inter-connection replay protection,
and, if the per-message MAC covers some connection counter, intra-
connection replay protection.
Note that in the composition of certain key derivation functions
(e.g. KDF_AES_128_CMAC, as used in TCP-AO [I-D.ao-crypto]), the
pseudorandom function (PRF) used in the KDF may require a key of a
certain fixed size as an input. For example, AES_128_CMAC requires a
128 bit (16 byte) key as the seed. However, for convenience to the
administrators/deployers, a specification may not want to force the
deployer to enter a PSK of exactly 16 bytes. Instead, a
specification may call for a sub-key routine that could handle a
variable length PSK, one that might be less than 16 bytes (see
[RFC4615], section 3, as an example). That sub-key routine would act
as a key extractor to derive a second key of exactly the required
length, and thus suitable as a seed to the PRF. This does NOT mean
that administrators are safe to use weak keys. Administrators are
encouraged to follow [RFC4086] as listed above. We simply attempted
to "put a fence around stupidity", in as much as possible.
A better option, from a security perspective, is to use some
representation of a device-specific assymetric key pair as the
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identity proof, as described in Section 3.4.2.
When it comes time for the KARP WG to design the re-usable model for
a KMP, The Guidelines for Cryptographic Key Management, RFC4107
[RFC4107] should be will be consulted.
[[QUESTION TO REVIEWERS: it may be worthwhile to pull the last few
paragraphs, along with some guidance along the same lines, into
section 4, in a new sub-section with a title something like "Security
tips for KARP design teams working on Routing Protocol reviews and
updates". Or maybe even into its own info document, "Security
Guidelines for KARP Design Teams".Thoughts?]]
The mechanisms that will be defined under this roadmap aim to improve
the security, better protect against more threats, and provider far
greater operational efficiencies than the state of things at the time
of this writing. However, none of these changes will improve
Internet security unless they are implemented and deployed. Other
influences must be brought to bare upon operators and organizations
to create incentives for deployment. Such incentives may take the
form of PCI-like industry compliance/certifications, well advertised
BCPs profiling the use of this roadmap's output, end-user demand or
insistance.
6. IANA Considerations
This document has no actions for IANA.
7. Acknowledgements
The outline for this draft was created from discussions and
agreements with Routing AD's Ross Callon and Dave Ward, Security AD's
Tim Polk and Pasi Eronen, and IAB members Danny McPherson and Gregory
Lebovitz.
Mat Ford and Bill Atwood provided reviews to -00.
Danny McPherson provided an extremely detailed and useful review of
-01.
8. Change History (RFC Editor: Delete Before Publishing)
[NOTE TO RFC EDITOR: this section for use during I-D stage only.
Please remove before publishing as RFC.]
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-00-00 original rough rough rough draft for review by routing and
security AD's
-00- original submission
o adds new category = multicast protocols in category section and
mentions mcast in group keying category description.
o add a lot of references where they did not exist before, or where
there were only place holders. Still more work needed on this.
o abstract filled in
o changed from standards track to informational (this was an
oversight in last draft).
o filled out threats section with detailed descriptions, and linked
to RPsec threats RFC
o made ascii art for the basic KMP framework
o added section on internal versus external peering and the
requirements decisions for them
o added security characterization section in sect 2, added sections
discussing internal vs external protocols, shared vs unique keys,
oob vs in-band keying
o incorporates all D Ward's feedback from his initial skim of the
document.
-01-
o Updated framework (Figure 1) diagram to include all listed and
described elements. Needs review and honing. Gregory Lebovitz
(GL).
o Added comment in protocols (Section 4.5) section that much of the
BGP/LDP Phase 1 work is already being done in tcp-ao and ao-
crypto. GL.
o Updated Scope making the 2 work phases more clear earlier in the
document. GL.
o Broke work items (Section 4.4) section into two Phases, 1 for
manual key update, and second for KMP work. GL.
o Re-org'd doc. Brought Threats (Section 2) section out into its
own top-level section. Did same with Categorization (Section 3)
section, leaving Roadmap section more focused. Moved ToDo list
and Change History to end of doc, after Acknowledgements. GL.
o added new sect 2.3 (Section 4.1) on main roadmap phases. Previous
section Common Framework (Section 4.3) moved to 2.4. Tim Polk
(TP).
o Added Section 2.3.1 Requirements for Phase 1 Routing Protocols'
Security Update (Section 4.2). This provides a nice starter set
of requirements for any work team. GL.
o Filled out text for Out vs In-band Key Mgmt (Section 3.4.3)
section, significantly. Changed the term from "in-band" to "in-
line".
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o Section Threats (Section 2) Clarified DoS threats in and out of
scope better. We are not preventing all DoS attacks. Just those
we can reasonably via authentication. TP.
o Sect In-band vs Out-of-Band (Section 3.4.3)clarified that In-band
does not mean in-band to Routing Protocol, but rather over IP
between the Routing Protocols, rather than pushed down by some
external management entity. TP.
o In roadmap (Section 3) section, added "it is also hoped that we
can create one kmp per category..." Also explained value of a
KMP. TP.
o Added "operators" to audience (Section 1.6) list. Matt Ford (MF).
o Described why BGP (and LDP) security is not deployed very often.
Added this Scope (Section 1.3) section, point 4. If mechanisms
aren't being deployed, why is that? What, if anything, could be
done to improve deployment? Tried to address these. Need
references (see To Do list below). MF.
o Added some text to security section to address this from MF: say
something here about the limitations of this approach, if any -
and refer back to the need for other pieces of the puzzle. May
need more work.
o Cleaned up text for multicast part of Message Type (Section 3.1)
section and Protocols (Section 4.5) section, clarifying PIM's two
message types, mcast and unicast, in both places. Bill Atwood
(BA).
o In section Protocols (Section 4.5), added references to 4601 and
PIM-SM-LINKLOCAL. BA.
o Editorial changes pointed out various folks.
-02-
o Re-submitted due to expiration. Text did not change. Substantive
update coming shortly.
o
o
- 03 -
o changed "BaseRP" to "Routing Protocol" throughout the doc - man
o filled out the Terminology section
o changed "KMART" to "KARP" in everything but the title, since the
-00 deadline had long since passed. Will change the title of the
doc to KARP as soon as the window re-opens.
o priorities in sect 4.6 changed. Added PIM-SM. Lowered OSPF and
BFD, based on feedback by a few people.
o many edits resulting from Danny McPherson's review.
o added "Brute Foce Attacks Against Password/Keys" to Threats
Section 2.1 section.
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o Significant updates to Security Considerations section
o Added a few references throughout to RFC3562
o 4.3 2nd to last P - added a comment to clarify that two parties
(or an org) must discuss ahead of time what they want their
connections' secruity properties to be. - dward
o added to 4.4 Phase 1 - New Section: Transition and Deployment
Considerations. ea wg must call out the operational transition
plan from old to new security. Best if don't bounce link. - dward
o added 3.3 (but not sure if this is right)- endpoint discovery
mechanisms? endpoint discovery mechanism (L2VPN, L3VPN, etc).
Discovery is much different security properties than passing
Routing updates. - dward
o More requirements: Added to 4.2: X - convergence SHOULD not be
affected by what we choose; adding security SHOULD not cause a
refresh of route updates or cause additional route updates to be
generated; adding auth should not be an attack vector itself.
AKA, the use of MD5 is so expensive that spoofing BGP packets w/
MD5 causes the control plane to be attacked because CPU went to
100% - dward
o updated stats on MD5 usage, and cited [ISR2008]. - mchpherson
9. Needs Work in Next Draft (RFC Editor: Delete Before Publishing)
[NOTE TO RFC EDITOR: this section for use during I-D stage only.
Please remove before publishing as RFC.]
List of stuff that still needs work
o RTG AD's or delegates: clean up the three definitions of route
message type categories. Need RTG Area folks input on this.
o More clarity on the work items for those defining and specifying
the framework elements and API's themselves.
o RTG AD's or delegates: text justifying RSVP and RSVP-TE and what
we think solving that problem may look like
o RTG AD's or delegates: more justification for why MANET and FORCES
are out of scope. Need ref for those RFCs.
o Danny McPherson: Get reference for BGP auth usage stats in Scope
(Section 1.3) section, item 4.
o
o security section: pull out security guidance to routing protocol
design teams stuff and place into its own section?
o
o
10. References
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10.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC4593] Barbir, A., Murphy, S., and Y. Yang, "Generic Threats to
Routing Protocols", RFC 4593, October 2006.
[RFC4948] Andersson, L., Davies, E., and L. Zhang, "Report from the
IAB workshop on Unwanted Traffic March 9-10, 2006",
RFC 4948, August 2007.
10.2. Informative References
[I-D.ao-crypto]
Lebovitz, G., "Cryptographic Algorithms, Use and
Implementation Requirements for TCP Authentication
Option", March 2009, <http://tools.ietf.org/html/
draft-lebovitz-ietf-tcpm-tcp-ao-crypto-00>.
[I-D.ietf-pim-sm-linklocal]
Atwood, W., Islam, S., and M. Siami, "Authentication and
Confidentiality in PIM-SM Link-local Messages",
draft-ietf-pim-sm-linklocal-09 (work in progress),
October 2009.
[I-D.ietf-tcpm-tcp-auth-opt]
Touch, J., Mankin, A., and R. Bonica, "The TCP
Authentication Option", draft-ietf-tcpm-tcp-auth-opt-08
(work in progress), October 2009.
[ISR2008] McPherson, D. and C. Labovitz, "Worldwide Infrastructure
Security Report", October 2008,
<http://www.arbornetworks.com/dmdocuments/ISR2008_US.pdf>.
[RFC1195] Callon, R., "Use of OSI IS-IS for routing in TCP/IP and
dual environments", RFC 1195, December 1990.
[RFC2328] Moy, J., "OSPF Version 2", STD 54, RFC 2328, April 1998.
[RFC2453] Malkin, G., "RIP Version 2", STD 56, RFC 2453,
November 1998.
[RFC3562] Leech, M., "Key Management Considerations for the TCP MD5
Signature Option", RFC 3562, July 2003.
[RFC3618] Fenner, B. and D. Meyer, "Multicast Source Discovery
Protocol (MSDP)", RFC 3618, October 2003.
Lebovitz & Expires May 9, 2010 [Page 41]
Internet-Draft KARP Roadmap November 2009
[RFC3973] Adams, A., Nicholas, J., and W. Siadak, "Protocol
Independent Multicast - Dense Mode (PIM-DM): Protocol
Specification (Revised)", RFC 3973, January 2005.
[RFC4086] Eastlake, D., Schiller, J., and S. Crocker, "Randomness
Requirements for Security", BCP 106, RFC 4086, June 2005.
[RFC4107] Bellovin, S. and R. Housley, "Guidelines for Cryptographic
Key Management", BCP 107, RFC 4107, June 2005.
[RFC4271] Rekhter, Y., Li, T., and S. Hares, "A Border Gateway
Protocol 4 (BGP-4)", RFC 4271, January 2006.
[RFC4301] Kent, S. and K. Seo, "Security Architecture for the
Internet Protocol", RFC 4301, December 2005.
[RFC4303] Kent, S., "IP Encapsulating Security Payload (ESP)",
RFC 4303, December 2005.
[RFC4306] Kaufman, C., "Internet Key Exchange (IKEv2) Protocol",
RFC 4306, December 2005.
[RFC4601] Fenner, B., Handley, M., Holbrook, H., and I. Kouvelas,
"Protocol Independent Multicast - Sparse Mode (PIM-SM):
Protocol Specification (Revised)", RFC 4601, August 2006.
[RFC4615] Song, J., Poovendran, R., Lee, J., and T. Iwata, "The
Advanced Encryption Standard-Cipher-based Message
Authentication Code-Pseudo-Random Function-128 (AES-CMAC-
PRF-128) Algorithm for the Internet Key Exchange Protocol
(IKE)", RFC 4615, August 2006.
[RFC4949] Shirey, R., "Internet Security Glossary, Version 2",
RFC 4949, August 2007.
[RFC5036] Andersson, L., Minei, I., and B. Thomas, "LDP
Specification", RFC 5036, October 2007.
[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 5226,
May 2008.
Lebovitz & Expires May 9, 2010 [Page 42]
Internet-Draft KARP Roadmap November 2009
Authors' Addresses
Gregory Lebovitz
Juniper Networks, Inc.
1194 North Mathilda Ave.
Sunnyvale, CA 94089-1206
US
Phone:
Email: gregory.ietf@gmail.com
Phone:
Email:
Lebovitz & Expires May 9, 2010 [Page 43]
+++++++++++++++++++++++
IETF-related email from
Gregory M. Lebovitz
Juniper Networks
g r e go r y d o t i e tf a t g m a i l do t c o m
- [karp] draft-lebovitz-kmart-roadmap-03.txt attach… Gregory M. Lebovitz